A comprehensive presentation on Chemistry of Amino acids with their clinical applications for MBBS , BDS, B Pharm & Biotechnology students to facilitate easy- learning.

1. Chemistry of Amino acids
with their clinical applications
Dr. Rohini C Sane

2. General Structural formula of - amino acids
Each Amino acid has
a specific functional group(R
group) besides amino(-NH3)
and carboxyl group(-COOH)
attached to same alpha()
carbon atom(the carbon next
to –COOH).
Most of the amino acids except
Proline are - amino acids.
General Structural formula
of - amino acids

3. Structural aspects of amino acids
Each Amino acid has a specific functional group(R) besides amino and
carboxyl group .
R
(amino group - acidic)H2N- C *–COOH (Carboxyl group -basic)
H
Exist in a biological system as ion of L- amino acids:
R
(amino group - acidic) H3N⁺- C *- COO⁻ (Carboxyl group -basic)
H
❖ *Asymmetrical carbon atom (attached to four different groups)
therefore amino acid exhibits optical isomers .
❖Glycine is optically inactive –absence of Asymmetrical carbon atom
→R=H

4. Amino acids function as building blocks of proteins
• Nitrogen content of proteins →16% by Kjeldahl method
• Nitrogen content x 6.25 = concentration of protein
• Protein are polymer of amino acids ( building blocks of proteins).
• Proteins+ HCl →hydrolysis→ L -alpha amino acids
• A1-A2-A3→(Acid /Enzyme Hydrolysis )→ A1 +A2 +A3
• 300 amino acids exist in nature ( animal ,plant and microbial system) .
• 20 standard L- amino acids commonly found in proteins of human body = 10
essential + 10 non essential amino acids
• 20 primary amino acids : coded by 61 Genetic codes(specific , universal ,
degenerate , non-overlapping)
• Dipeptide = 2 amino acids & one peptide bond ,tripeptide = 3 amino acids & 2
peptide bonds , polypeptide = >10 amino acids
• Pseudopeptide : a peptide bond is formed by carboxyl group other than that
present in the alpha position

5. Chemistry of proteins
❖Definition : Proteins is derived from Greek word “ proteios which
means primary or holding first place ” .
Chemistry of proteins :
1. Organic compounds
2. High molecular weight
3. Rich in nitrogen
4. Important for life
5. Abundant occurrence in nature
6. Polymers of amino acids linked by peptide bonds (-CO-NH) in
specific and unique sequence which defines both their three
dimensional structure determining biological functions.

6. Chemistry of amino acids
• All 20 Amino acids found in proteins have a specific functional group (R group)
besides amino(-NH2) and carboxyl group(-COOH) attached to the same alpha()
carbon atom(the carbon next to –COOH).
• Most of the amino acids except Proline are -amino acids.
• Amino acids differ from each other in their side chains on R groups attached to
alpha carbon atom therefore vary in structure ,size and electric charges (which
has influence on solubility of amino acids in water).
• When R group contains additional carbon atoms in a chain ,they are designated ,
,  and  preceding out from the  carbon atom.
• Each of 20 standard amino acids have been assigned three letter abbreviations
and one letter symbol. (e.g. Glycine has abbreviated name Gly and one letter
symbol G).
• All the amino acids found in protein are exclusively of the L-configuration (the
same absolute configuration as L- Glyceraldehyde)and hence L –amino acid .

7. ,,  and  additional carbon atoms in R group preceding out from the  carbon atom in
amino acid structure

CH3-CH-COO-
NH3
+
  
-OOC-CH2-CH2- CH-COO-
NH3
+
    
CH2-CH2-CH2-CH2- CH-COO-
NH3
+ NH3
+
Glutamic acid with  carboxyl group (R group)
 Alanine
I
I
I
I Lysine with  amino group (R group)
  Alanine
 
CH3-CH-COO-
NH3
+l

8. Three letters and one letter abbreviation for 20 primary amino acids in the Genetic Code
Amino acid Three letter
abbreviation
One letter
abbreviation
Alanine Ala A
Arginine Arg R
Asparagine Asn N
Aspartic Acid Asp D
Cysteine Cys C
GlutamicAcid Glu E
Glutamine Gln Q
Glycine Gly G
Histidine His H
Isoleucine Ile I
Amino acid Three letter
abbreviation
One letter
abbreviation
Leucine Leu L
Lysine Lys K
Methionine Met M
Phenylalanine Phe F
Proline Pro P
Serine Ser S
Threonine Thr T
Tryptophan Trp W
Tyrosine Tyr Y
Valine Val V

9. Systematic namesof 20 primary amino acids in the Genetic Code
Amino acid Systematic name
Alanine 2-aminopropanoicacid
Arginine 2-amino-5-gaunidovalericacid
Asparagine -Amideof2-aminosuccinicacid
Aspartic Acid 2-aminosuccinicacid
Cysteine 2-amino-3-mecaptopropanoic
acid
GlutamicAcid 2-aminoglutaricacid
Glutamine -amideof2-aminoglutaricacid
Glycine 2-Aminoaceticacid
Histidine 2-amino-3-imidazole-4-propanoic
acid
Isoleucine 2-amino-3-methylpentatonicacid
Amino acid Systematic name
Leucine 2-amino-4-methylpentatonicacid
Lysine 2,6-diaminohexanoicacid
Methionine 2-amino-4-methylthiobutanoicacid
Phenylalanine 2-amino-3-phenylpropanoicacid
Proline 2-Pyrrolidinecarboxylicacid
Serine 2-amino-3-methyl propanoicacid
Threonine 2-amino-3-hydroxybutanoicacid
Tryptophan 2-amino-3-(3-indolyl)propanoicacid
Tyrosine 2-amino-3-(4-hydroxyphenyl)
propanoicacid
Valine 2-amino-3-methylbutanoicacid

10. R groupandMolecular weights of twenty amino acids
Amino acid Special group/
R group
Molecular
weight
Alanine Methyl 89
Arginine Guanidium 174
Asparagine Amide 132
Aspartic Acid -carboxyl 133
Cysteine Sulfhydryl 121
GlutamicAcid -carboxyl 147
Glutamine Amide 146
Glycine Hydrogen 77
Histidine Imidazole 155
Isoleucine Branchedchain 131
Amino acid Special group/
R group
Molecular
weight
Leucine Branchedchain 131
Lysine -amino 146
Methionine Thioester 149
Phenylalanine Benzene 165
Proline Pyrrolidine 115
Serine Hydroxyl 105
Threonine Hydroxyl 119
Tryptophan Indole 204
Tyrosine Phenol 181
Valine Branchedchain 117

11. Molecular weights of twenty amino acids

12. The Genetic Codes for 20 primary amino acids
20 primary amino acids : coded by 61 Genetic codes(specific , universal , degenerate , non-
overlapping)

13. L and D Isomers of amino acids
The proteins are composed of L-amino acids .
L and D Isomers of amino acids are mirror images and also called enantiomers.

14. Isomers of Glyceraldehyde
Left CHO CHO
OH C H H C OH
CH2OH CH2OH
L- Glyceraldehyde D- Glyceraldehyde
Mirror images ( enantiomers)
All the amino acids found in protein of human body are exclusively of the L –
configuration (the same absolute configuration as L –glyceraldehyde)and hence L
–amino acid .

15. Structure of Proline (Imino acid)
The side chains of Proline ( pyrimidine group) and its -amino group
form a ring structure. It is an imino acid or heterocyclic acid and has
secondary amino group i.e. imino group( -NH) not a primary amino
group NH2 .
H
imino group → C COOH
-carbon atom
H2C CH2
CH2
Structure of Proline (Imino acid)

16. Classification of amino acids

17. Classification of amino acids
❖Classification of amino acids based on:
1. Nutritional requirement
2. Metabolic fate
3. Chemical charge in the solution
4. Structure of a side chain of amino acid
5. Nature or polarity of the side chain of the amino acids

18. Classification of amino acids based on nutritional requirement : Essential and
nonessential Amino acids
• Protein seen in human body contain 20 different amino acids. These amino acids
are required for normal growth and during physiological stress.
• Out of these ,10 can be synthesized in our body from the products(carbon
skeletons formed from metabolism of carbohydrates even when they are absent in
dietary proteins ) →non- essential / dispensable amino acids
e.g. Glycine , Alanine , Serine ,Cysteine ,Aspartic Acid, Asparagine, Glutamic Acid,
Glutamine , Proline , Tyrosine
• Remaining 10 amino acids (their carbon skeletons) can not be synthesized in our
body and needed to be supplemented in diet / food proteins for growth
→essential / indispensable amino acids
e.g. Methionine , Arginine ,Threonine , Tryptophan ,Valine, Isoleucine, Leucine ,
Histidine , Phenylalanine, Lysine (MATT VIL PHLY/ PVT TIM HALL)
A deficiency of an essential amino acid impairs protein synthesis and leads to
negative nitrogen balance( nitrogen excretion exceeds nitrogen intake).
➢Arginine and Histidine are semi- essential amino acids.

19. Essential and nonessential Amino acids
Non-essential/dispensable amino acids (10)
• Methionine
• Arginine
• Threonine
• Tryptophan
• Valine
• Isoleucine
• Leucine
• Phenylalanine
• Histidine
• Lysine
Essential / indispensable amino acids(10)
• Glycine
• Alanine
• Serine
• Cysteine
• Aspartic Acid
• Asparagine
• Glutamic Acid
• Glutamine
• Proline
• Tyrosine
M
A
T
T
V
I
L
P
H
L
Y
Synthesized
by
Endogenous
metabolites

20. Classification based of amino acids on metabolic fate
1. Glucogenic amino acids (precursor of Glucose ,Glycogen ): after
removal of amino group of amino acid , the carbon skeleton can be
converted to glucose (enter Glucogenic pathway). Fourteen amino acids
are Glucogenic. e.g. Alanine ,Aspartic acid ,Glycine
2. Ketogenic amino acids : after removal of amino group of amino acid , the
carbon skeleton can be converted to ketone bodies (acetoacetic acid) → fat
synthesis (via Acetyl Co) e.g. Leucine
3. Glucogenic & Ketogenic amino acids : after removal of amino group of
amino acid , the carbon skeleton splits into two parts one of which can be
converted to ketone body (enter ketogenic pathway) other part can be
converted to glucose (Glucogenic pathway ) e.g. Phenylalanine ,Tyrosine,
Tryptophan ,Alanine, Isoleucine , Lysine

21. Classification based of amino acids on metabolic fate
Glucogenic amino acids Ketogenic amino acids Glucogenic&Ketogenicaminoacids
Glycine
Alanine
Serine
Threonine
Cysteine
Methionine
Valine
Aspartic acid
Glutamic acid
Asparagine
Glutamine
Arginine
Histidine
Proline
Leucine Phenylalanine
Tyrosine
Tryptophan
Lysine
Isoleucine

22. Classification of amino acids based on the chemical structure of side
chain of the amino acid
❖Based on the chemical nature of the side chains(R group) , amino acids are
categorized into seven major classes:
1. Amino acids with Aliphatic side chain (GAVLI)
2. Amino acids containing Aromatic side chain
3. Amino acids containing Hydroxyl group(OH)
4. Amino acids containing Sulfhydryl group(SH)
5. Acidic Amino acids & their amides
6. Basic Amino acids(HAL)
7. Based on the polarity ,amino acids are classified into two major classes
a. polar (hydrophilic)
b. non-polar (hydrophobic)
8. imino acid or heterocyclic acid : has secondary amino group i.e. imino
group( -NH) not a primary amino group NH2 e.g. Proline

23. Amino acids containing Aliphatic side chain (GAVLI) : I. Classification of amino acids
based on the chemical structure of side chain of the amino acid
1. Glycine(Gly = G) : synthesis of
ammonia ,bile salts, Creatine ,
Formate, Glucose, Glutathione ,
Heme, purine bases, oxalate ,
Serine and detoxification
2. Alanine(Ala=A):participation in
transamination and ammonia
transport
3. Valine (Val=V): glycogenic amino
acid
4. Leucine(Leu=L):ketogenic amino
acid
5. Isoleucine(Ile=I): glycogenic and
ketogenic amino acid

24. Amino acids containing Aromatic side chain : II. Classification of amino acids
based on the chemical structure of side chain of the amino acid
1. Phenylalanine(Phe =F): contains
benzene group
2. Tyrosine(Tyr=Y):contains phenol
group
Functions of Phe &Tyr :synthesis of
Adrenaline, Thyroxine (hormones)
and melanin(skin pigment)
3. Tryptophan(Trp =W): it is
heterocyclic amino acid and
contains indole group
Functions of Trp : synthesis of fat ,
Glucose, Niacin(NAD+ ,NADP+),
Serotonin, Melatonin, Indole acetic
acid and 5-hydroxy indole acetic acid
(HIAA)

25. Amino acids containing Hydroxyl group(OH): III. Classification of amino
acids based on the structure of side chain of the amino acid
1. Serine(Ser=S): synthesis of Glucose ,
Glycine , Alanine, Cysteine(Cystine) ,
Ethanolamine (Choline), Sphingomyelins,
one carbon metabolism Selenocysteine ,
phosphoproteins and phosphatidyl serine
2. Threonine(Thr=T):formation of
Glycine, acetaldehyde, phosphoproteins
amino acetone (Pyruvate, Lactate)and
alpha-keto butyrate (Propionyl CoA)
3. Tyrosine(Tyr=Y) contains phenol group
: synthesis of Melanin, epinephrine,
Thyroxine

26. Amino acids containing Sulphur group : IV. Classification of amino acids
based on the chemical structure of side chain of the amino acid
1. Cysteine(Cys =C) : Synthesis of Glucose, Creatine,
Glutathione, Taurine , Coenzyme A, active sulfate
and Cystine (S-S bonds play role in secondary
structure of proteins)
2. Methionine(Met=M) : dietary source Sulphur in
human body , initiation of protein biosynthesis,
synthesis of Cystathionine, Polyamines and a
donor of methyl group after activation. Acceptor
of methyl group gets methylated
(transmethylation reactions) .
Methionine + Acceptor→ methylated Acceptor
+Homocysteine
e.g. Epinephrine ,Choline, Melatonin

27. Cysteine and Cystine are Sulphur containing Amino acids :
IV. Classification of amino acids based on the chemical structure of side
chain of the amino acid
Cystine has disulfide ( S-S ) as a functional group . It is formed from Cystine
(Dicysteine)after oxidation. Cystine on reduction yields two Cysteine molecules.
Two Cysteine residues can connect two polypeptide chains by formation of
Interchain disulfide bonds or links . e.g. Insulin

28. Acidic Amino acids & their amides : V. Classification of amino acids based on
the chemical structure of side chain of the amino acid
These are amino acids are
Acidic in solution and mono-
amino dicarboxylic acids .
1.Aspartic acid (Asp=D):
synthesis of Urea, Glucose,
Purine and Pyrimidine bases
2.Glutamic acid (Glu=E):
synthesis of GABA(inhibitory
neurotransmitter in brain),
Purine and Pyrimidine bases
3. Asparagine(Asn=N) amide of
Asp
4.Glutamine (Gln=Q)-amide of
Glu: temporarystorageofammonia
andplaysroleinacid–basebalance

29. Basic Amino acids(HAL) : VI. Classification of amino acids based on the chemical
structure of side chain of the amino acid
These are amino acids are basic in solution
and diamino-monocarboxylic acids .
1.Histidine (His=H) contains imidazole group :
contributes acid-base balance and oxygen
transport by hemoglobin, synthesis of
histamine(regulation of gastric HCl secretion)
2.Arginine(Arg =R) contains guanidinium:
synthesis of Urea, Ornithine and Nitric oxide
(bactericidal, vasodilator ,relaxation of smooth
muscles, neurotransmitter)
3.Lysine(Lys=K) contains -amino group:
forming salt bridges for maintenance of
structural conformation of protein, Trimethyl
Lysine: synthesis of Carnitine( beta-oxidation
of fatty acids , beneficial in treatment of AIDS
and myocardial dysfunction)

30. Selenocysteine: 21st amino acid
❖Selenocysteine:
•21st amino acid present in human body Protein (incorporated in 25proteins)
• Instead of SH(sulfhydryl)group in Cysteine, SeH (Selenium) is present in
Selenocysteine
• Nomenclature by IUPA / IUBMB : three letter Abbreviation as SeCys or SeC
and one letter symbol as U for selenocysteine
• have separate codon UGA that normally functions as stop codon/signal.
• has specialized eukaryotic t-RNA i.e. t-RNA Sec : with different primary and
secondary structure (a long variable region arm,9 base pairs in acceptor
stem, substitution at several well conserved base positions )
• Incorporated as such into proteins during protein biosynthesis and proteins
containing selenocysteine are called as Selenoproteins .

31. Structure of Selenocysteine
Cysteine Selenocysteine
H H
NH2 C CH2 SH NH2 C CH2 SeH
COOH COOH
❖Selenocysteine : has a structure similar to Cysteine ,but with Selenium atom
taking place of the usual sulfur.

32. Selenoproteins
• Selenoprotein : protein containing one or more Selenocysteine residues
• Present in some human enzymes (Selenoproteins) e.g. Glutathione
peroxidase , Glycine reductase , Formate dehydrogenase , Thioredoxin
reductase, Deiodinase(converts thyroxine to triiodothyronine)
• The UGA codon is made to encode Selenocysteine by the presence of
selenocysteine insertion sequence (SECIS) element of 3 ’-untranslated
region(3’ UTR) in eukaryotic m-RNA.
• Eukaryotic (SECIS) element : has characteristic nucleotide sequences and
secondary structure in base pairing patterns. 3’ UTR can direct UGA codons
to encode Selenocysteine residues.
• Prokaryotic (SECIS) element : located immediately following the UGA codons
within the reading frame for the Selenocysteine.

33. Pyrrolysine(Pyl): 22ndamino acid
❖Pyrrolysine(Pyl):
• 22nd amino acid present in human body Protein.
• have separate codon that normally function as a stop signal.
• is a Lysine in an amide linkage to substituted –pyrroline-s-carboxylate.
• is present in methyl transferase enzyme of certain bacteria.

34. Amino
acid Functions of amino acids:1
Ala synthesis of proteins, participation in transamination and ammonia transport
Arg synthesis of proteins ,Urea, Ornithine and Nitric oxide (bactericidal, vasodilator , relaxation of smooth muscles,
neurotransmitter )
Asn synthesis of Asp
Asp synthesis of proteins ,Urea, Glucose, Purine and Pyrimidine bases, participation in Malate –Aspartate shuttle
Cys Synthesis of proteins ,Glucose, Creatine, Glutathione, Taurine , Coenzyme A, bile salts, active sulfate and Cystine (S-S
bonds play role in secondary structure of proteins)
Glu synthesis of proteins, Glucose, Ammonia, Histidine , Proline , Arginine , Glutathione, N –acetylgltamte,
GABA(inhibitory neurotransmitter in brain),  carboxyglutamate, Purine and Pyrimidine bases
Gln temporary storage of ammonia and plays role in acid-base balance , synthesis of proteins, Ammonia, Amino sugars,
Purine and Pyrimidine bases, Detoxification
Gly synthesis of proteins , ammonia ,bile salts, Creatine , Formate ( participation in one carbon metabolism) , Glucose,
Glutathione , Heme (Hemoglobin and Myoglobin) ,Purine bases, Oxalate , Serine and Detoxification
His synthesis of proteins , acid –base balance and oxygen transport by hemoglobin, synthesis of histamine(regulation of
gastric HCl secretion)
Leu ketogenic amino acid
Ile glycogenic and ketogenic amino acid

35. Amino
acid Functions of amino acids:2
Lys forming salt bridges for maintenance of structural conformation of protein, Trimethyl lysine: synthesis of Carnitine
( beta oxidation of fatty acids , beneficial in treatment of AIDS and myocardial dysfunction)
Met dietary source Sulphur in human body , initiation of protein biosynthesis, synthesis of Cystathionine, Polyamines
and a donor of methyl group after activation. Acceptor of methyl group gets methylated (transmethylation
reactions for synthesis of Epinephrine ,Choline, Melatonin)
Phe synthesis of proteins ,Glucose ,fat ,Adrenaline, Noradrenaline, Thyroxine , T3 hormones, Melanin ,Dopamine
Pro synthesis of Glutamate and - ketoglutarate
Ser synthesis of proteins ,Glucose , Glycine , Alanine, Cysteine(cystine) , Ethanolamine (Choline), Sphingomyelins,
Selenocysteine , Phosphoproteins and Phosphatidyl serine , participation in one carbon metabolism
Thr formation of Glycine, Acetaldehyde, phosphoproteins amino acetone ( Methyl glyoxyl, Pyruvate, Lactate)and alpha-
keto butyrate (Propionyl CoA)
Trp synthesis of fat , Glucose, Niacin(NAD+ ,NADP+), Serotonin, Melatonin, Indole acetic acid and 5-hydroxy indole
acetic acid (HIAA)
Tyr synthesis of proteins ,Melanin, Epinephrine, Norepinephrine ,Thyroxine , T3 hormones , Dopamine
Val synthesis of proteins, glycogenic amino acid
SeH Incorporated as such into proteins during protein biosynthesis and proteins containing selenocysteine are called as
Selenoproteins.
Pyl is present in methyl transferase enzyme of certain bacteria.

36. ClassificationofaminoacidsbasedonChemicalchargeontheaminoacidinthesolution
❖Classes of amino acids based on Chemical charge in the solution:
1. Neutral amino acids
2. Acidic amino acids
3. Basic amino acids

37. Neutral amino acids : Class of amino acids based on Chemical charge on
amino acid in the solution
Glycine Serine Phenylalanine
Alanine Threonine Tyrosine
Valine Cysteine Tryptophan
Leucine Methionine Asparagine
Isoleucine Proline Glutamine
These amino acids are Neutral in solution and mono amino-monocarboxylic acids
having one amino group and one carboxylic group.

38. Classification of amino acids based on charge they carry in solution
Criteria Acidic amino acids Basic amino acids Neutral amino acids
Net charge at pH 6.0
on amino acids
Negative Positive Neutral ( equal number
of Positive & Negative
charge)
Synonym Mono amino
dicarboxylic acid
Diamino mono
carboxylic acid
Mono amino mono
carboxylic acid
Examples Aspartic acid
Glutamic acid
Lysine
Arginine
Histidine
Glycine , Alanine,
Serine, Threonine,
Cysteine , Methionine,
Valine , Leucine ,
Isoleucine, Asparagine ,
Glutamine, Phenylalanine
Tyrosine , Tryptophan,
Proline

39. Class Subclass Amino
acid
Structural formula with R
/special group
Systematic
name
Abbreviations Mol
weight
Aliphatic Polar/
uncharged
Glycine H-CH-COOH
NH2 Hydrogen
Amino
Acetic acid
Gly G 77
Aliphatic Non-polar Alanine H3C-CH-COOH
NH2 Methyl
2-Amino
propanoicacid
Ala A 89
Aliphatic Non-polar
Branched
chain
Valine H3C
CH-CH-COOH
H3C NH2 branched chain
2-amino-3-
methylbutanoic
acid
Val V 117
Aliphatic Non-polar
Branched
chain
Leucine H3C branchedchain
CH-CH2-CH-COOH
H3C NH2
2-amino-4-
methyl
pentatonicacid
Leu L 131
Aliphatic Non-polar
Branchedchain
Isoleucine H3C
CH2-CH-CH-COOH
H3C NH2 branchedchain
2-amino-3-
methyl
pentatonicacid
Ileu I 131
Aliphatic amino acids
I
I
I
I
I

40. Class of
amino
acid
Subclass Aminoacid Structural formula with R
/special group
Systematic
name
Abbreviations Mol
weight
Hydroxyl Polar/
uncharged
Serine CH2-CH-COOH
OH NH2
hydroxyl
2- Amino-
3-hydroxy
propanoic
acid
Ser S 105
Hydroxyl Polar/
uncharged
Threonine H3C –CH-CH-COOH
OH NH2
hydroxyl
2- amino-
3-hydroxy
butanoic
acid
Thr T 119
Hydroxyl Non-polar/
Aromatic
Tyrosine OH- -CH2-CH-COOH
NH2
hydroxyl
2- Amino-3-
(4-hydroxy-
phenyl)
propanoic
acid
Tyr Y 181
Amino acids with hydroxyl group
I I
I I
I

41. Classof
aminoacid
Subclass Aminoacid Structural formula
with R /special group
Systematic
name
Abbreviations Mol
weight
Sulphur
containing
Polar
uncharged
Cysteine CH2-CH-COOH
SH NH2 Sulfhydryl
2- Amino-
3-mercapto
propanoic acid
Cys C 121
Sulphur
containing
Cystine CH2-CH-COOH
S NH2 Disulfide
S
CH2-CH-COOH
NH2
Sulphur
containing
Non-polar
Aliphatic
Methionine CH2- CH2-CH-COOH
S-CH3 NH2 Thioether
2- amino-4-
(methyl thio)
hydroxybutanoic
acid
Met M 149
Sulphur containing amino acids
I I
I
I
I
I
I
I
I

42. Class
of
amino
acid
Subclass Aminoacid Structural formula with R
/special group
Systematic
name
Abbreviations Mol
weight
Acidic Polar
–vely
charged
Asparticacid HOOC-CH2-CH-COOH
NH2
Beta carboxyl
2-amino
succinic
acid
Asp D 133
Acidic Polar
–vely
charged
Glutamicacid HOOC-CH2-CH2-CH-COOH
NH2
Gamma carboxyl
2-amino
glutaric
acid
Glu E 147
Acidic Polar Asparagine H2N- C –CH2 –CH-COOH
O NH2
Amide
Asn N 132
Acidic Polar Glutamine H2N-C-CH2-CH-CH-COOH
O NH2
Gln Q 146
Acidic amino acids & their amides
I
I
II
II
I
I

43. Class
of
amino
acid
Subclass Amino
acid
Structural formula with R
/special group
Systematic
name
Abbreviations Mol
weight
Basic Polar
+vely
charged
Lysine CH2 –CH2-CH2-CH2- CH-COOH
NH2 NH2
ε- amino
2,6 diamino -
hexanoic acid
Lys K 146
Basic Polar
+vely
charged
Arginine H-N-CH2 –CH2-CH2-CH- COOH
C =NH NH2
NH2
Guanidinium
2-amino -5-
gaunido
valeric acid
Arg R 174
Basic Polar
+vely
charged
Aromatic
Histidine Imidazole
-CH2 –CH-COOH
NH2
2- Amino-1H-
imidazole-4-
propanoic
acid
His H 155
Basic amino acids
HN N
I I
II
I

44. Classof
amino
acid
Subclass Aminoacid Structuralformulawith
R/specialgroup
Systematicname Abbreviations Mol
weight
Aromatic Polar Histidine - -CH2-CH-COOH
NH2 Imidazole
2- Amino-1H-
imidazole-4-
propanoic acid
His H 155
Aromatic Nonpolar Phenylalanine - -CH2-CH-COOH
NH2 benzene
2- Amino-3-
phenyl propanoic
acid
Phe F 165
Aromatic Nonpolar Tyrosine HO- -CH2-CH-COOH
NH2
phenol
2-Amino-3-(4-
hydroxy-phenyl)
propanoicacid
Tyr Y 181
Aromatic Nonpolar Tryptophan 2- Amino-3-(3-
indolyl )
propanoic acid
Trp W 204
Aromatic Nonpolar Proline
(iminoacid)
OH- 2-Pyrrolidine
carboxylic acid
Pro P 115
Aromatic amino acids
-CH2-CH-COOH
NH2
HN N
-COOH
NH
I
I
I
I

45. Amino acids
Hydrophilic
(polar)
Negatively
charged
Aspartic acid
Glutamic acid
Positively
charged
Lysine
Arginine
Histidine
Uncharged
Serine,Threonine
Asparagine,Glutamine
Glycine,Cysteine
Hydrophobic
(non-polar)
Aliphatic side
chain
Alanine,Valine
Leucine,
Isoleucine,Proline,
Methionine
Aromatic side
chain
Tyrosine
Phenylalanine
Tryptophan
Classificationaminoacidsbasedupon
polarity:1

46. Classification amino acids based upon polarity:2
1. Non polar amino acid : hydrophobic ( water repellant) and lipophilic : no charge on R
group either aliphatic or aromatic side chain e.g. Alanine, Valine, Leucine ,Isoleucine ,
Proline, , Methionine, Phenylalanine , Tyrosine, Tryptophan
Parts of protein made up of these amino acids will be hydrophobic and found in interior
of the protein that function in an aqueous environment and on the surface of proteins such
as membrane proteins that interact with lipids .
2. Polar amino acid : hydrophilic : no charge on R group or non –ionic
e.g. Hydroxyl (OH) of : Serine ,Threonine, Tyrosine 
Sulfhydryl  (SH) of : Cysteine (hydrophobic when present interior of protein)
Amide  of : Glutamine ,Asparagine Hydrogen  of : Glycine
 Enabling amino acid to form hydrogen bonds with water.
3. Polar amino acid with positive charge on R group within physiologic pH or ionic polar
side chain : hydrophilic ( water loving) : basic amino acids 
e.g. (HAL) Histidine ,Arginine ,Lysine
4. Polar amino acid with Negative charge on R group at physiologic pH or ionic polar side
chain :hydrophilic ( water loving) : acidic amino acids 
e.g. Aspartic acid ,Glutamic acid
 Found on the outside of proteins that function in an aqueous environment and in the
interior of membrane –associated proteins.

47. Classification amino acids based upon polarity:3

48. Classification amino acids based upon polarity:4

49. Classification amino acids based upon polarity:5

50. Importance of amino acids
❖Importance of amino acids :
1. Formation of proteins: amino acids joined by peptide bonds to form proteins
and peptides
2. Formation of Glucose : Glucogenic amino acids are converted to Glucose in
body
3. Transport and storage of ammonia : Glutamine play role in transport and
storage of amino nitrogen in the form of ammonia
4. Enzyme activity : Cysteine has an important role in activity of certain enzymes
5. Buffer : both free amino acids and some amino acids found in protein can
potential act as buffer . Histidine can serve as the best buffer at physiological
pH .
6. Detoxification reactions : Glycine , Cysteine, and Methionine are involved in
the detoxification of toxic substances .
7. Formation of Biologically important compounds in the body

51. Role of amino acids in formation of Biologically important compounds in human body
Amino acid Function in synthesis of biomolecule
Tyrosine Adrenaline and Noradrenaline(increase cardiac output and blood
pressure), Thyroxine ,T3 hormones , Melanin(skin
pigment),Dopamine (increase blood pressure)
Tryptophan Niacin(vitamin), NAD+, NADP+, Serotonin (stimulates cerebral
activity and regulates behavior), Melatonin
Glycine,Arginine,Methionine Creatine
Glycine , Cysteine Bile salts(Sodium Glycocholate )
Glycine Heme(Hemoglobin ,Myoglobin)
Aspartic acid ,Glutamic
acid, Glutamine
Purine bases
Asparticacid,Glutamicacid Pyrimidine bases
Beta alanine Coenzymes A

52. Role of amino acids formation of Biogenic amines in human body
Amino acid Synthesis of Biogenic amines Functions of Biogenic amines
Tyrosine Tyramine Vasoconstrictor (increases blood pressure)
Tryptophan Tryptamine increases blood pressure
Serotonin Stimulates cerebral activity and regulates
behavior
Melatonin Circadian rhythms
Serine Ethanolamine Forms choline
Cysteine Taurine Constituent of bile acids (taurocholic acid)
Histidine Histamine Vasodilator , promotes synthesis of HCl and
pepsin
Glutamic acid - amino butyric acid Inhibitory neurotransmitter in brain
Phenylalanine Dopamine Synthesis of Epinephrine and Norepinephrine

53. Non-standard amino acids

54. Non-standard amino acids
❖Besides the 20 standard amino acids present in the protein structure, several
other amino acids are biologically important. These include
1. D-amino acids
2. Amino acid derivatives found in protein
3. Non-protein amino acids: performing specialized functions (not
substituents of proteins→ amino acids derived from sources other than
protein )
4. Alpha()amino acids found in plants /animals

55. D-amino acids
❖D-amino acids are seen in
a. small amounts in microorganisms
b. as constituents of certain antibiotics (produced by microorganisms)
e.g. Actinomycin-D/ Valinomycin/ Gramicidin-S/polymyxin .
c. Involved in synthesis of bacterial cell wall peptidoglycans
d. Involved in synthesis of cross-links in bacterial cell wall e.g. D- Glutamic
acid & D-Alanine
e. D- Serine and D –Aspartate found in brain tissue

56. Amino acids derivatives in protein
❖Amino acids derivatives in protein: In addition to the common amino
acids ,a small number of modified amino acids are found in proteins
and formed by specific modification of one of 20 amino acids after
protein biosynthesis .
❖Derivatives of Amino acid are very important for protein structure
and functions.

57. Amino acid derivatives in proteins after synthesis of proteins ,some amino acids are modified)
Aminoacidderivativesinproteins Derived from Functions
Cystine linkage of two Cysteine side
chains-SH (sulfhydryl) through
disulphide bond -S-S
provides stability to the three dimensional structure
of protein
4-Hydroxy Proline & 5-
Hydroxy Lysine
Derived from Hydroxylation
Proline & Lysine
occur in only few proteins like Collagen in
connective tissue
Desmosine and isodesmosine Oxidation and crosslinking of 4
Lysine residue side chains
found in connective tissue protein ,elastin
Gamma carboxyglutamate Carboxylation of glutamic acid side
chain
occurinmanyclottingproteininblood(e.g.Prothrombin).Inability
toformGammacarboxyglutamateleadstobleedingdisorders.
Phosphoserine,phosphotyrosine
,phosphothreonine
Phosphorylation of Hydroxyl group
of Serine , Threonine , Tyrosine
found in regulatory protein
N–methyl lysine Methylation of Lysine occur in myosin (contractile protein from muscle)
Selenocysteine-21st aminoacids Instead of SH (sulfhydryl) group
in cysteine, SeH (Selenium)
Essential residue in several enzymes e.g.
Glutathione peroxidase
Methylated,phosphorylatedor
acetylatedaminoacids
Amino acids found in Histone (the proteins found in
association with DNA)and ribosomal proteins

58. Biologically important amino acid derivatives
Biologically important amino
acid derivatives
Derived from amino
acid
Functions
Dopamine Tyrosine aneurotransmitter
Gammaaminobutyricacid(GABA) Glutamicacid aneurotransmitter
Histamine Histidine a mediator of allergic reactions
Ornithine and citrulline Arginine essential for urea synthesis
(intermediates urea biosynthesis)
Cycloserine Serine an antituberculotic drug
Azaserine Serine Ananticancerdrug(inhibitoroftumorgrowth)

59. Role of Cystine in protein structure
Oxidation
reduction
formation of Cystine : linkage of two
Cysteine side chains-SH (sulfhydryl)
through disulphide bond -S-S
Role of Cystine in protein structure :provides stability
to the three dimensional structure of protein

60. Hydroxyproline in Collagen structure

61. Collagen
Collagen :rich in Glycine and rare amino acids hydroxyproline, hydroxylysine

62. Desmosine :crosslinkingof4Lysineresiduesidechainsinelastin
condensation
3 Allysine + Lysine Desmosine
Desmosine :found in connective tissue protein ,elastin

63. Gamma Carboxy Glutamic acid is component of clotting factors: Biologically
important amino acid derivatives
Gamma Carboxy Glutamic acid: occur in many clotting proteins in blood ( e.g. Prothrombin).
Inability to form Gamma carboxyglutamate leads to bleeding disorders.

64. Gammacarboxyglutamateinclottingproteininblood
Prothrombin
Inability to form Gamma carboxyglutamate leads to bleeding disorders.

65. Phosphoserine,phosphothreonine,phosphotyrosine in regulatory protein

66. Histones : the proteins found in association with DNA

67. Histone octamers
The double stranded DNA helix is wrapped around the core proteins namely histones which are
basic in nature .The core is composed of two molecules of histones ( H2A,H2B,H3,and H4).Each
core with two turns wrapped around it (150bp) is termed as nucleosome ( the basic unit of
chromatin).

68. Methylated, phosphorylatedoracetylatedaminoacids
ofHistonesplayroleingeneexpression

69. Histone : has Methylated/ Acetylated / Phosphorylated Lysine residues
( Biologically important amino acid derivatives)
➢Acetylation of Histone → activation of transcription
➢ De -acetylation of histone → depression of transcription
➢Sometimes, Histones are fixed to Small Ubiquitin Related Modifier(SUMO).
SUMOylation of histones is seen during repression of transcription.

70. Naturally occurring Non-standard and non-protein amino acids:1
Non-protein amino acids  : some 300 amino acids have been found in cells
but that have variety of functions but are not found as substituent of proteins.
Non-protein amino acids Occurrence /Significance
3, 4 dihydroxy phenylalanine (DOPA) Precursor of Melanin
5- hydroxy tryptophan Precursor of Serotonin
Homoserine Threonine, Aspartate , Methionine metabolism
Homocysteine Methionine biosynthesis
Homocitruline Urine of normal children
Alpha-amino butyric acid Animal and plant tissue
Pipecolic acid Metabolic product of o- Lysine breakdown in
mammals
Saccharopine Intermediateinlysinebiosynthesisbyyeastandneurospora

71. Naturally occurring Non-standard and non-protein amino acids:2
Amino acid Function of Non-standard and non-protein amino acids
3, 4 -Dihydroxy phenylalanine
(DOPA)
A neurotransmitter and serves as a precursor for
melanin pigment synthesis
Creatinine Derived from muscle creatine and excreted in urine
Ovothiol Sulphur containing amino acid found in fertilized egg
and acts as an antioxidant

72. Naturally occurring Alpha -amino acids as non-protein amino acids
Alpha-Amino acid Function of Non-standard and non-protein amino acids
Ornithine  Intermediate of Urea cycle
Citrulline Intermediate of Urea cycle
Arginosuccinic acid Intermediate of Urea cycle
Thyroxine (T4 ) Thyroid hormone derived from Tyrosine
Triiodothyronine (T3 ) Thyroid hormone derived from Tyrosine
S-Adenosyl Methionine (SAM) Methyl group donor in biological system
Homocysteine IntermediateinMethioninemetabolism,riskfactorforcoronaryheart
disease(CHD)
Histamine Mediator of allergic reactions
Homoserine IntermediateinAspartate,Threonine ,Methioninemetabolism
Azaserine An antibiotic, anticancer drug
Cycloserine Antituberculotic drug

73. Non-alpha and non-protein amino acids
Non-alpha and non-protein amino acids Functions of Non-alpha amino acids
Beta(β)Alanine→aminogroupinβposition Component of vitamin Pantothenic
acid & Coenzyme A
Beta(β)amino isobutyric acid End product of pyrimidine metabolism,
found in urine of patients with an
inherited metabolic disease
Gamma()Amino butyric acids(GABA) A inhibitory neurotransmitter in brain
tissue produced from Glutamic acid
Delta Aminolaevulinic acid (ALA) Intermediate in synthesis of porphyrin
(finally Heme)
Taurine Found in association with bile
acids(taurocholate), free form in cells

74. Functions of Rare amino acids
Rare amino acids Chemistry Functions
4-Hydroxy Proline &
5-Hydroxy Lysine
Derived from Hydroxylation
Proline & Lysine
Occurinonlyfew proteinslike
Collageninconnectivetissue
 -Alanine  Amino group attached to the
-carbon atom
OccurindipeptideCarnosineand
Anserineofmuscle.Itisformedin
degradationofPyrimidines,
CytosineandUracil.
D-amino acids
Food proteins and human
body proteins are built up of
only L– amino acids.
NH2 group of amino acid is
located on alpha carbon atom.
Present in the bacterial cell
wall proteins and a few
antibiotics like Gramicidin
Ornithine and Citrulline Presentinthehumanbody,inthis
formtakepartinthebiosynthesisof
Ureainliverandarenotpresentin
proteins

75. Non-standard Amino acids used as drugs
Non-standard Amino acids
used as drugs
Mechanism of action Therapeutic use
D-Penicillamine
(D-dimethylglycine)
Chelates copper ions A chelation therapy for
Wilson’s disease
N-Acetylcysteine An Antioxidant Cystic fibrosis
Gabapentin
( -amino butyrate linked to
cyclohexane )
Inhibitor of Gamma()Amino
butyric acids(GABA)-a
neurotransmitter in brain
tissue
Anticonvulsant

76. Physical properties of amino acids

77. Physical properties of amino acids
1. Solubility : soluble in water/ insoluble in organic solvents ( polar solvents) and
insoluble in non- polar solvents (benzene)
2. Melting points : > 200⁰C
3 . Color : colorless crystals
4. Taste:
Sodium Glutamate : increases taste & flavor
Aspartames: artificial sweeter contain Aspartic acid and Phenylalanine
5. Absolute configuration : same as L – Glyceraldehyde& hence L - amino acids
6. Optical activity : dextrorotatory / levorotatory at pH 7.0 due to presence
asymmetrical carbon atom
Taste Amino acids
Sweet Glycine ,Alanine
Sour/bitter Arginine ,Isoleucine
Tasteless Leucine

78. Optical activity of amino acids
All amino acids have at least one asymmetrical carbon atom which confer
Optically activity to amino acids . Isoleucine ,Threonine have two
asymmetrical carbon atoms and each has four diastereoisomers .
Glycine (has no asymmetrical carbon atom) is optically inactive.
Asymmetricalcarbonatom:attachedtofourdifferentgroupsattachedtothesamecarbonatom

79. Acid-base behavior of Amino acids

80. Ionization of amino acids
❖Due to ionizing property of amino acids , amino acids exert :
1. Acid-base behavior : depend on the amino and carboxy groups
attached to the alpha-carbon and on the basic ,acidic or other
functional groups represented by R.
2. Amphoteric properties( Zwitterion formation): at physiological pH
7.4 ( pH range 7.35- 7.45), carboxy group is dissociated and amino
group is protonated. This kind of ionized molecule with coexistent
negative and positive charges (i.e. carboxylate ( COO-) and N+H3)is
called a dipolar ion or ampholyte.
3. Buffering activity : free amino acids and some amino acids present
in protein can potentially act as buffer due to presence of ionizable
carboxylic , amino group and ionizable group in side chain.

81. Acid-base behavior of Amino acids
Amino acid behaves as an acid in alkaline medium :
R +OH- R
H3N+- CH- COO- H2N- CH- COO- +H2o
alkali added anion
A proton of H3N+ is dissociated which with OH- ion forms water .
Amino acid behaves as a base in acidic medium :
R +H + R
H3N+- CH- COO- H3N+- CH- COOH Protonated
acid added Cation
A proton from added acid is accepted by COO- group to form COOH.
Thus, in acidic medium , Amino acid exist as a cation and in alkaline medium it
exist as an anion. At certain pH (isoelectric pH), it exist as a Zwitterion .
R
It carries both positive and negative charge (neutral ion). H3N+- CH- COO-
No net charge, doesn't move in the electric field.

82. Existence of an amino acid as Cation, Anion and Zwitterion
H
R- CH- COOH
NH2
H H
R- CH- COOH R- CH- COO-
N+H3 NH2
H
R- CH- COO-
N+H3
Zwitterion
(isoelectric pH)
Cation
(low pH)
Anion
(high pH)
Amino acidH +
H +
H +
H+

83. Isoelectric pH of amino acid (or protein)
and zwitterions

84. Amino Acids as Ampholytes
❖Amino Acid behaves as Ampholyte or are amphoteric in nature i.e. it can
function as acid as well as base ( can donate proton and accept proton-H+
respectively ) .
❖Amino Acids occurs as:
1. Cation at low pH (acidic): both the NH2 and COO- groups are protonated to
N+ H3 and COOH.
2. Anion at high pH (alkaline): COOH groups looses a proton (H+
) behave as an
acid to form water with OH- group.
3. Zwitterion at isoelectric pH( pH at which an amino acid bears no net
charge- termed as pI ) . At this pH ,the molecule dose not move in an
electrical field. These neutral molecular species are termed as
Zwitterions/dipolar ions and carries both positive and negative charges .
The pI differ for the different amino acids and is based on the number and
charge of the ionizable groups.
4. Solubility and buffering capacity at pI is minimum.

85. Amino Acid behaves as an Ampholyte
Cation 
Anion

Physiological pH

86. Isoelectric pH of amino acid (or protein) and zwitterion
❖Each monoamino monocarboxylic acid has two ionizable groups : 1. -COOH
and 2. -N+H3
Their relative strengths are given as pK values.
e.g. Alanine
pK1 of -COOH= 2.1 (Alanine can function as buffer pH range from 1.1-3.1 )
pK2 of -N+H3 = 9.8 (Alanine can function as buffer pH range from 8.8-10.8 )
Zwitterion form occurs at average of pK1 and pK2
i.e. pK1 + pK2 = 2.1 + 9.8 = 6 = pI (isoelectric pH of Alanine)
2 2
Average of pK1 and pK2 is known as isoelectric pH (pI )
❖Isoelectric pH of amino acid (or protein) is that pH at which zwitterion
exists. At this pH , it bears no net charge and does not move in electric
field which facilitates physical separation of amino acids or proteins.
❖Every amino acid can function as buffer in the range one pH unit on either
side of its pK value.(e.g. Alanine : 2.1  1 and 9.8  1)

87. Isoelectric pH of Glycine and its zwitterion
❖Each amino acid has two ionizable groups : 1. -COOH and 2. -N+H3
Their relative strengths are given as pK values.
e.g. Glycine
pK1 of -COOH= 2.4 (Glycine can function as buffer pH range from 1.4-3.4 )
pK2 of -N+H3 = 9.8 ( Glycine function as buffer pH range from 8.8-10.8 )
Zwitterion form occurs at average of pK1 and pK2
i.e. pK1 + pK2 = 2.4 + 9.8 = 6.1 = pI (isoelectric pH of Glycine )
2 2
Average of pK1 and pK2 is known as isoelectric pH (pI)
❖The buffering action is maximum in and around or at pK1 and pK2 and
minimum at Isoelectric pH of amino acid .
❖At physiological of blood (pH 7. 4) or the intracellular space (pH7.1) ,both carboxyl
and amino group are completely ionized i.e. carboxylate (COO-) and N+H3.
Uncharged or unionized amino acid cannot exist.

88. Titration curve of Glycine
• The buffering action is maximum in and around or at pK1(2.4) and pK2(9.8)
and minimum at Isoelectric pH (6.1)of amino acid .

89. Sorenson Formal Titration of Glycine solution
Excess formaldehyde is added to 1ml of Glycine solution.
Formaldehyde converts amino group of Glycine into neutral dimethyl derivative.
UptakeofhydrogenionsreleasedbyionizationofcarboxylionsofGlycineisblocked.
Titration of 1 ml of Glycine solution is completed to the end point against 1
ml of 1N NaOH.
1 ml of 1N NaOH is utilized by 1ml of Glycine solution.

90. Titration of a neutral amino acid with alkali
Starting with an acidic medium (cation) ,a zwitterion is obtained by
addition of one equivalent of alkali (OH-) and anion is formed by addition
of one more equivalent of alkali.
e.g. Titration of amino acid Alanine with alkali is explained below .
R R R
H3N+- CH- COOH H3N+- CH- COO- H2N- CH- COO-
Cation Zwitterion Anion
Charge +1 at pH 1.0 net charge zero at pI =6.0 Charge -1 at pH 11.0
Protonated
( proton containing )
one equivalent of alkali addedone equivalent of alkali added
H2OH2O

91. Titration of amino acids
1N HCl added dropwise to amino acid solution at particular pH e.g. pH 1.0
50% of molecules are cation form and 50% zwitterion form
This pH is pK1 (with regard to COOH).
If more HCl is added ,more molecules become cationic in nature and solubility
increases.
Titrate solution of amino acid from Isoelectric point with NaOH, the molecules
acquire anionic form.
50% of molecules are anion form, that pH is pK2 (with regard to NH3)
The isoelectric pH (pI) for monoamino monocarboxylic amino acid is calculated as
pI = (pK1+ pK2) /2 e.g. pI of Glycine = (2.4 +9.8)/2 = 6.1

92. Ionization of Aspartic acid with alkali and acid
❖Addition of one equivalent of alkali (OH-) and anion is formed by addition of one more
equivalent of alkali.
e.g. Titration ( ionization) of amino acid Aspartic acid with alkali is explained below:
COOH +OH
- COO- +OH
- COO- +OH
- COO-
CH- N+H3 CH-N+H3 CH-N+H3 CH- NH2
CH2 +H+ CH2 +H+ CH2 +H+ CH2
COOH pk1=2.1 COOH pK3=3.9 COO- pK2=9.8 COO-
Net Charge +1 Net Charge Net Charge -1 Net Charge -2
at pH 1.0 nil
❖In case of amino acids having more than two ionizable groups,
correspondingly there will be more pK values e.g. Aspartic acid has three pK
values 2.1, 9.8, 3.9.

93. Titration curve of Aspartic acid with alkali

94. Titration curve of Aspartic acid with alkali

95. Histidine functions as a buffer
• Every amino acid can function as buffer in the range one pH unit on either
side of its pKa value. Maximum buffer capacity occur at pH = pKa.
• However ,ranges of pKa value, are away from pH of blood (7.4 ). Thus, in
general amino acids are not useful as buffers except Histidine has pK2 =6.0
of imidazole group . Therefore, Histidine functions as buffer.
• Hemoglobin functions as a buffer since it contains large number of
Histidine residues (38 out of 574 amino acids in a Hb molecule).
• Carbon dioxide adds to amino group of Histidine to form Carbamino-Hb.
This reaction occurs at alkaline pH and serves as a mechanism for
transport of carbon dioxide from tissue to the lungs.
Hb –NH2 + CO2→ Hb –NH- COOH ( Carbamino-Hb)

96. pka values of amino acids
Amino acid Pk1 of alpha
carboxyl group
pK2 of alpha amino
group
Pk3 of extra
ionizable
extra ionizable
group present
pI
Glycine 2.4 9.8 6.1
Valine 2.3 9.6 6.0
Serine 2.2 9.2 5.7
Cysteine 1.9 10.3 8.2 Sulfhydryl 5.1
Glutamine 2.2 9.1 5.6
Aspartic acid 2.1 9.8 3.9 Beta carboxyl 3.0
Glutamic acid 2.2 9.6 4.3 Gamma carboxyl 3.2
Lysine 2.2 8.9 10.5 - amino 9.7
Arginine 2.0 9.0 12.5 guanidium 10.8
Phenylalanine 2.6 9.2 5.9
Tyrosine 2.2 9.1 10.1 phenol 5.7
Tryptophan 2.4 9.4 5.9
Histidine 1.8 9.2 6.1 Imidazole 7.6

97. Chemical properties of amino acids

98. Chemical properties of amino acids
❖Chemical properties of amino acids are due to the :
1. Carboxyl group
2. Amino group
3. Side chain group R
❖Several widely used reactions of amino acids implicated for their:
i. Detection
ii. Measurement
iii. Identification

99. Chemical properties of amino acids
1. Functional groups of amino acids :
a. Carboxyl group (COOH)
b. Amino group (NH2)
2. Reactions of amino acids with Alkali :
COOH + NaOH → COONa (Salt )
3. Reactions of amino acids with Alcohol:
COOH + ROH → COOR (Ester )
4. Decarboxylation of amino acids
5. Reaction of amino acid with Ammonia
6. Reactions of amino acids with NH2 group
7. Reactions of amino acids with Ninhydrin
8. Reactions of - amino group of amino acids with fluorescamine /Dabsyl chloride
9. Transamination reactions of amino acids
10. Oxidative deamination of amino acids
11. Peptide bond formation

100. Reactions of amino acids with Alcohol
3. Reactions of amino acids with Alcohol:
COOH + ROH → COOR (Ester )
• Hydroxyl amino acids can form esters with phosphoric acid .
• Serine and Threonine residues of proteins are involved in formation
of phospho proteins.
• Hydroxyl groups can form O-glycosidic bonds with carbohydrate
residues to form glycoproteins.

101. Decarboxylation of amino acids : Chemical properties of amino acids
4. Decarboxylation of amino acid produces important amines with biological
action:
R –CH-COO⁻ → R-CH (Amine ) + CO2
N⁺H3 N⁺H3
Histidine → Histamine ( Vasodilator →deceases blood pressure ,released in
allergic conditions, regulates gastric HCl and pepsin secretion, causes asthma )
Glutamic acid→ GABA ( Gamma Amino Butyric Acid → inhibitor of
neurotransmitter )
5- hydroxy tryptophan→ 5- hydroxy tryptamine (=Serotonin→aneurotransmitter)
Lysine →Cadaverine
Tyrosine →Tyramine (waste product)

102. Functions of Histamine
Mediator
of allergic
reactions
Vasodilator
and lowers
the blood
pressure
Stimulates gastric HCl and pepsin secretion
Excessive production
of histamine causes
asthma
IgEmoleculesbindwithmastcellswhichreleaseHistamine

103. Histidinemia
❖Histidinemia :
1. Frequency :1: 20,000
2. Molecular basis : defect in Histidase
3. Clinical manifestation :
a. Elevated plasma histidine levels
b. Increased excretion of histidine and imidazole pyruvate in urine
c. Mental retardation
d. Defect in speech
e. No treatment will improve the condition of the patients
➢ Histamine test meal :

104. Basal gastric secretion is collected for one hour .
Administration of Histamine ( 0.04 mg/ kg body weight) subcutaneously.
Gastriccontentsareaspiratedforthenextonehour(at15minutesintervals).
The acid content is measured in all these samples .
Interpretation : increased gastric HCl in Histidinemia
Histamine test meal
ThetestisbasedontheprinciplethatHistaminestimulatesgastricHClsecretion.

105. Reaction of amino acid with Ammonia: Chemical properties of amino acids
5. Reaction of amino acid with Ammonia
AA-COOH + NH3 → Amide
Carboxylic acid + Ammonia → Amide
Aspartate + NH3 → Asparagine (Amide)
Glutamic acid + NH3 → Glutamine (Amide)
These amides are components of protein
structure.
The amide group of Glutamine serves as the
source of nitrogen for nucleic acid synthesis.
amide group of Glutamine and Asparagine can
form N -glycosidic bonds with carbohydrate
residue to form glycoproteins.

106. Glutamine synthetase in Glutamine synthesis

107. Reactions of amino acids with NH2 group :Chemical properties of amino acids
6. Reactions of amino acids with NH2 group :
a. Amino acid + NH3 → Salt
b. Ammonia + HCl → Salt (N⁺H3Cl⁻)
c. Amino acid +acid → Salt

108. Reactions of amino acids with Ninhydrin :7Chemical properties of amino acids
6. Reac
Amino acid + Ninhydrin → Keto acid +NH3+ CO2 + Hydrindantin (after heating)
Hydrindantin +NH3 + Ninhydrin → Ruhemann’s purple
Reactions of amino acids with Ninhydrin

109. Ninhydrin reaction of -Amino acid
COO
-
+ H3N +- C - H
R
+ 3 H2O + H +
Ninhydrin→ Ninhydrin
-Amino acid

Heat H
CO2 + R- C
O
C= N-C H
O
II
C
O
II
C
O
II
C
C
II
O
C
II
O
C
II
O
C
II
O
I
I
OH
C
OH
OH
C
OH
Purple
pigment
O
II
C

110. Applications of Reactions of amino acids with Ninhydrin reagent
❖Applications of Reactions of amino acids with Ninhydrin reagent :
1. Colorimetric estimations of amino acids
2. Staining in chromatographic strips
✓Proline in which amino group is present in the form of imino group , yields
yellow product.

111. Forensic Applications of Ninhydrin Test
Fingerprint

112. Reactions of - amino group of amino acids with fluorescamine /Dabsyl chloride:8
Fluorescamine /Dabsyl chloride/Dansyl chloride/1-fluoro 2, 4 dinitrobenzene:
react with - amino group of amino acids to form colored /fluorescent derivatives .
❖Advantages of reactions :
1. Unlike ninhydrin , the intact R group of amino acids remains the part of product ,
so that derivatives of different amino acids can be distinguished.
2. Product of reaction are derivatives of these reagents and absorb light . Hence they
facilitate the detection and quantification of amino acids
Reactions of - amino group of
amino acids with
Product of reactions Application of
reactions
Fluorescamine fluorescent derivatives with intact
R group of amino acids
Detectionofnanogram
quantitiesofaminoacids
Dabsyl chloride ,Dansyl chloride,
1-fluoro 2, 4 dinitrobenzene
fluorescent derivatives with intact
R group of amino acids
fluorescentderivativesof
reactionarestableatharsh
conditions.

113. Transamination reactions of amino acids: 9. Chemical properties of amino acids
Transfer of amino group to Keto acids
Keto acid 1 + Amino acid 1 ↔ Amino acid 2 + Keto acid 2
Alanine transaminase = ALT = SGPT

114. Transamination reactions of amino acids
Transfer of amino group to keto acids
AST
GOT and GPT ,Tyrosine transaminase, branched chain transaminase occur
in liver.

115. Importance of Transamination reactions of amino acids
❖Importance of Transamination reactions of amino acids:
➢ are reversible.
➢ bring about deamination of amino acids (the catabolism)
➢involved in interconversion of amino acids and biosynthesis of non-essential
amino acids.
➢are specific to one of the amino acids and other substrate is always alpha
ketoglutarate. Consequently , the combined action of these transaminases is
to tunnel amino group to alpha ketoglutarate and form L –glutamate .
➢Glutamate undergoes Oxidative deamination by Glutamate dehydrogenase
to form alpha ketoglutarate and ammonia ( utilized in urea cycle) .

116. Oxidative deamination of amino acids: 10.Chemical properties of amino acids
• Amino acid + O2→ Keto acids + NH3
• Glutamate → α-KGA ( alpha keto
glutaric acid) + Ammonia
• Importance of Oxidative deamination
of amino acids :

117. Peptide bond formation: 11. Chemical properties of amino acids
❖Peptide bond formation :
1. The most important reaction of amino acid
2. A peptide contains two or more amino acid residues joined together covalently
by a amide linkage ,termed as a peptide bond.
3. Formation of peptide bond = a covalent bond is formed between the -amino
group of one amino acid and - carboxyl group of another amino acid by
removal of a water molecule.
4. Oligopeptide: a few amino acids joined together covalently by peptide bonds
5. Polypeptide : many amino acids joined together covalently by peptide bonds
6. Hydrolysis of peptide bonds : by proteolytic enzymes i.e. peptidases or
peptidases

118. Peptide bond formation: 11.Chemical properties of amino acids
• Formation of peptide bond = a
covalent bond is formed
between the  carboxyl group of
one amino acid and  amino
group of another amino acid by
a amide linkage with removal of
a water molecule.
• Successive amino acids are
joined by peptide bonds
( -CO-NH) in proteins .
Dipeptide :two amino acids one peptide bond

119. Analytical techniques associated with amino acids

120. Ultra- violet light absorption by Tyrosine and Tryptophan in protein
Tyrosine and Tryptophan in protein is responsible for ultra violet light absorption of
proteins with maximum 280nm (nanometers).

121. Absorption spectra of aromatic amino acids
• Presence of 2 aromatic amino acids Tyrosine and Tryptophan in
protein is responsible for ultra-violet light absorption of proteins
with maximum 280nm (nanometers).
• The contribution of Phenylalanine to ultra violet light absorption of
proteins at 280nm is negligible .
• Since most proteins contain Tyrosine ,measurement of ultra-violet
light absorption of proteins at 280nm in spectrophotometer is an
extremely rapid and convenient means of estimation of protein
content of a solution.

122. Gel filtration for amino acid determination
Identification of amino acids is done using chromatography /Gel filtration.
UV spectrophotometry /colorimetric analysis is used for quantitation of amino acids.

123. Principle of Paper Chromatography technique for separation of amino acids
• Principle of Paper Chromatography technique for separation of amino acids :
separation of mixture of amino acids is effected by the continuous partition of
the amino acids between stationary water phase adsorbed on the filter paper
and moving organic solvent flowing over the filter paper( mobile phase) .
• Mobile phase : an organic solvent layer of mixture of Butanol : Acetic acid :
Water in proportion of 4:1:5

124. Technique of Paper Chromatography for separation of amino acids
❖Technique of Paper Chromatography for separation of amino acids :
1. A small amount of the mixture of amino acids (in solution) to be separated is
applied on the filter paper( Whatmann 1 or3 ) at one point on a pencil line .
2. Pure amino acids (standard) are spotted on the same line at the distance of 2 cm
apart from each other .
3. The paper is supported vertically so that the edge near the pencil line is dipping in
organic solvent ( taken in a trough).
4. A bell-jar is kept covered the paper and the trough.
5. The solvent rises slowly in upward direction and it carries each amino acid of
mixture and standard amino acids.
6. Sufficient time is allowed for the solvent to reach almost the opposite edge of the
paper. The bell- jar is removed.
7. Quickly mark the edge of solvent with pencil .This is known as a solvent front .
8. The solvent is allowed to evaporate from the filter paper .

125. Detection andidentificationofaminoacidsseparatedbyPaperChromatography
❖Detection of amino acids separated by Paper Chromatography:
The filter paper is sprayed with ninhydrin reagent and kept in hot air oven for few
seconds .
• The height of each amino acid is measured from the origin (the pencil line).Similarly
the distance of solvent front is measured from the pencil line.
• The ratio of distance moved by each amino acid and distance moved by the
solvents is calculated .Ratio is known as Rf value.
❖identification of amino acids separated by Paper Chromatography:
• Rf value is a characteristic property of each amino acid.
• Rf value of each amino acid of unknown mixture is compared with Rf value of
standard / known pure amino acid.

126. Applications of PaperChromatography
❖Applications of Paper Chromatography :
• Detection of amino aciduria due to inborn errors of metabolism (due to
deficiency / absence of enzymes, defect in absorption→ excretion amino
acids in urine in significant amounts )
• When another solvent system in a perpendicular direction of paper is
employed , it is two dimensional Paper Chromatography and separates the
amino acids more distinctly.
➢ Detection of sugars excreted in various of glycosuria .

127. Detection andidentificationofaminoacidsseparatedbyPaperChromatography
The filter paper is sprayed with ninhydrin reagent and kept in hot air oven for few seconds .
Rf value of each amino acids is its characteristic property. Thus ,the amino acids in the
unknown mixture can be identified fairly well by comparing their Rf values with those of pure
amino acids.

128. Detection andidentificationofaminoacidsseparatedbyPaperChromatography
comparison of RF value with standard amino acids
Rf value of each amino acids is its characteristic property. Thus ,the amino acids in the
unknown mixture can be identified fairly well by comparing their Rf values with those of pure
amino acids.

129. Applications of PaperChromatography
Glycosuria Excreted sugar in urine
Lactosuria Lactose
Galactosuria Galactose
Pentosuria Pentose
Essential Fructosuria Fructose
➢Detection of sugars excreted in various of glycosuria:

130. Principle of Ionexchangechromatographyforseparationofaminoacids/proteins
• Principle of Ion exchange chromatography for separation of amino acids /
proteins: is based on differences in charges of amino acids / proteins at a given
pH .
• Cylindrical glass column is filled with insoluble matrix to which charged groups
have been attached .
• Cation exchange resin : matrix with negative groups
Cation exchange resins exchanges its cation (H+) withanothercation(C+)in solution :
H+R- + C+  C+R- + H+
• Anion exchange resin : matrix with positive groups
Anionexchangeresinsexchangesitsanion(A-)withanotheranion(B-)in solution:
R+A- + B-  R +B- + A-

131. Separation of amino acids / proteins in Cation exchange resin
• Separation of amino acids / proteins in Cation exchange resin : ions with
greater positive charge bind more tightly to Cation exchange resin than do
ions with negative charges. Thus, amino acids /proteins with largest
negative charges will pass through column before amino acids /proteins
with small negative charge.
• Thus , amino acids /proteins can move out at different times and rates from
the column on application of eluting buffer at a given pH.
• Many times a pH gradient is applied and amino acids /proteins are eluted
from column in stepwise manner.

132. Mechanism of cation exchange in ion exchange
chromatography in an amino acid analyzer
• The negatively charged sulfonate (SO3
-) groups attract and bind
cations such as H+ , Na+ or cationic forms of amino acids .
• At pH 3.0, most amino acids are cations but differ in net strength of
their positive charges and thus in degree to which they can displace
Na+ from the fixed anionic groups .
• Lysine would be bound most tightly because of its two N+H3 groups
whereas Glutamic acid and Aspartic acid would be bound least
tightly since they have least amount of positive charge at pH 3.0.
• The binding of amino acids to ion exchange resins is also affected by
their degree of adsorption or their solubility in the resin particles .

133. Anionic site
SO3
- Na+
SO3
- Na+ + N
+
H
3
- CHR-COOH  Amino acid
SO3
-N
+
H
3
-CHR-COOH
SO3
-N
+
H
3
-CHR-COOH + 2 Na
+
Resin
particle
cation exchange
Resin
particle
Mechanism of cation exchange in ion exchange chromatography

134. Chromatographic analysis of amino acids on cation exchange resin
Amino acids eluted at
150 cm column pH 3.25
and 0.2 N Sodium citrate
Amino acids eluted at
150 cm column pH 4.25
and 0.2 N Sodium citrate
Amino acids eluted at 15
cm column pH 5.28 and
0.35 N Sodium citrate
1.Aspartic acid 6.Glycine 15.Lysine
2.Threonine 7.Alanine 16.Histidine
3.Serine 8.Cysteine 17.NH3
4.Glutamic acid 9.Valine 18.Arginine
5.Proline 10.Methionine
11.Isoleucine
12.Leucine
13.Tyrosine
14.Phenylalanine

135. Elution profile of standard amino acids of PTH ( 20 pmoles)
Using Edman’s degradation technique , amino acid sequencing can be completed within a
few hours by automatic machines .

136. Schematic diagram of horizontal strip electrophoresis tank : Technique for Separation of
amino acids /proteins
+ _
Electrophoresis support
Filter paper wicks
anode compartment
cathode compartment
Barbiton
Buffer
PH 8.6
Strip-Cellulose acetate /Whatmann No.1paper
Power supply—0.5-10 mA
Stains specific for proteins : Amido black 10B, Bromophenol blue, Azocarmine B

137. Separation of amino acids using paper electrophoresis
Anode
Buffer chamber
Cathode
Anions Cations
Spotcontaining
aminoacid
mixture
Filter paper strip
+ -
T1
T2
Paper is dried ,sprayed with ninhydrin
and heated ,revealing location of the
amino acids . The amino acids are
identified by comparison with the
position of authentic amino acids as
markers.
Before applying current
After
applying
current→

138. Separation of amino acids using paper electrophoresis
1. A drop of solution ( 15- 20 l) of the amino acid mixture is dried on the paper.
2. The paper strip is moistened with a buffer(barbiton buffer of pH 8.6 or veronal
buffer)at a given pH and placed between cooling plates .
3. The ends of the strip are immersed in a buffer from the electrode compartments.
4. Application of direct current electric field (0.5- 10 mA)separates amino acids based on
their net electric charge at the pH used.
5. Amino acids that are cations at the pH used will migrate towards the cathode (negative
electrode), anionic amino acids will move to anode (positive pole) as indicated at time
T1.
6. At the end of process, paper is dried ,sprayed with ninhydrin and heated ,revealing
location of the amino acids .
7. The amino acids are identified by comparison with the position of authentic amino
acids as markers.

139. Technique of Separation of amino acids using paper electrophoresis
A drop of solution of the amino acid mixture is dried on the paper.
ThepaperstripismoistenedwithabufferatagivenpHandplacedbetweencoolingplates.
The ends of the strip are immersed in a buffer from the electrode compartments.
Application of direct current electric field separates amino acids based on their net
electric charge at the pH used.
AminoacidsthatarecationsatthepHusedwillmigratetowardsthecathode(negativeelectrode), anionic
aminoacidswillmovetowardsanode(positivepole)asindicatedattimeT1.
Attheendofprocess,paperisdried,sprayedwithninhydrinandheated,revealinglocationoftheaminoacids.
Theaminoacidsareidentifiedbycomparisonwiththepositionofauthenticaminoacidsasmarkers.

140. Principle of Thin layer chromatography for separation of amino acids
❖Principle of Thin layer chromatography for separation of amino acids : is
based on separation partition or distribution of components between two
liquid phases .
❖Basis of partition or distribution of components:
1. Adsorption
2. Partition
3. Ion exchange
4. Molecular exclusion

141. SampleapplicationinTechniqueofThinlayerchromatographyforseparationofaminoacids
• • • • • • • • origin
Score mark
/solvent front
Visualization: the locating agent is usually sprayed with Shandon gun onto dried plate
after development.
Identification: after visualization , by spraying with locating agent ,the individual
component can then be identified by their characteristic color and Rf value.

142. Technique of Thin layer chromatography for separation of amino acids
❖ Technique of Thin layer chromatography for separation of amino acids:
➢ Stationary phase: layer of water bound to a uniform layer of adsorbent
/solid support such as silica gel or alumina powder)
➢Mobile phase : organic solvent →passes through Thin layer on plate and
compounds distribute themselves between two phases based on their
partition coefficients .
➢Separation: is carried out in a glass tank( covered ) containing the developing
solvents. Amino acids / proteins mixture is applied on the Stationary phase.
Plate is then placed in solvent . Hydrophilic and hydrophobic amino acids
/Proteins with move at different rate and thus can be separated.
➢Detection :ninhydrin reagent gives a blue or purple color with amines and
amino acids

143. Causes of Aminoaciduria
1. Genetic Mutations ( mutated amino acids not metabolized ,amino acid
concentration in serum increases →Aminoaciduria )
2. Liver Diseases (amino acid not utilized for synthesis of proteins )
3. Renal diseases ( reabsorption of amino acid prevented → excreted in
urine )
4. Heavy metal poisoning ( reabsorption of amino acid hindered → excreted
in urine )

144. Examples of Aminoaciduria:1a
Aminoaciduria Urinaryexcretionof
aminoacid
DeficientEnzyme(metabolismofsulfuraminoAcids-
Methionine,Cysteine,Cystine)/metabolicdefect
Cystinuria(Cystine-
lysinuria)
Cysteine,Ornithine,
Arginine,Lysine
DefectivecarriersystemforCOAL,Transportabnormalityin
bowelmucosa,Defectinrenalreabsorption
Cystinosis Cystine,generalized
aminoaciduria
ImpairmentinCystineutilization(defectinlysosomalfunction),
impairmentincystinereductase?
HomocystinuriaI Homocysteine Cystathioninesynthase
HomocystinuriaII Homocysteine N5N10-MethyleneTHFreductase
HomocystinuriaIII Homocysteine N5N10-MethylTHF-homocysteinemethyltransferase
Cystathionuria Cystathionine Cystathionase,homoserinehydratase
Small quantity of amino acids excreted in the normal urine . Certain inborn errors of
metabolism ,due to absence or deficiency of enzymes or defect in absorption, some amino
acids are excreted in large amount . Chemical test and chromatography technique can be
applied for their detection.

145. Clinical features and Management for Aminoaciduria:1b
Aminoaciduria Clinical features Management
Cystinuria
(Cystine-lysinuria)
Somaticandoccasionalmentalretardation,renalcalculi with
theircomplications
Restrictedintakeof cystine,
Penicillamine ,high intake of
water, alkalis and fluids , and
some time low-methionine
intake
Cystinosis
( cystine storage
disease)
Depositionof Cystinecrystalsinlysosomesof
reticuloendothelialsystem(spleen,liver,lymphnodes,
kidney,bonemarrow),renalfailure→generalizedamino
aciduria→deathwithintenyearsafterbirth
Restrictedintakeof cystine,high
intakeoffluids
Homocystinuria mentalretardation,spasticparaplegia,occasionalconvulsions,
cataract,lenticulardislocation,friablehair,malarflush,
thromboembolicdisease,bonechanges
Restrictedintakeofmethionineand
cysteine,supplementationof
pyridoxine
Cystathionuria mentalretardation,congenitalmalformation,talipes,
deafness,abnormalearsandsensation,renalcalculi,with
theircomplications,thrombocytopenia/highphenylalanine
Large doses of pyridoxine

146. Examples of Aminoaciduria:2a
Aminoaciduria Urinaryexcretionofaminoacid Deficient Enzyme/ metabolic defect
Glycinuria Glycine Defectiverenalabsorption
Primaryhyperoxaluria Glycine Glycineoxidase/transaminase
HyperprolinemiaTypeI Proline Prolineoxidase/dehydrogenase
Histidinemia Histidine Histidase
Hartnup’sdisease Tryptophan Impairmentinabsorptionandortransportof
Tryptophanandotherneutralaminoacidsfrom
intestine,renaltubulesandprobablybrain
Maplesyrupurinedisease Branchedchainaminoacidandketo
acids
Branchedchain-ketoaciddehydrogenase
Hypervalinemia Valine(branchedchainaminoacid) Valinetransaminase
Isovalericacidemia Isovalericacid IsovalerylCoAdehydrogenase
Intermittentbranchedchain
ketonuria
Valine,Leucine,Isoleucine Variantoftheaboveenzyme(lesssevere)

147. Clinical features and Managementfor Aminoaciduria:2b
Aminoaciduria Clinicalfeatures Management
Glycinuria Increasedtendencyfortheformationofoxalaterenal stones Decreasedintake
ofoxalateindiet,
increasedwater
intaketofacilitate
excretionof
oxalate
Primaryhyperoxaluria Increasedtendencyfortheformationofoxalaterenal stonesandoxalosis
HyperprolinemiaTypeI Familialnephritis,deafness,renalhypoplasia,epilepsy,abnormalEEG
Histidinemia Slurred,inarticulatespeech,variableincidencesof mentalretardation Lowhistidinediet
Hartnup’sdisease mentalretardationinsomecases,pellagra-likeskinrash,ataxia, andother
cerebellarsigns
Supplementation
ofnicotinicacid
Maplesyrupurinedisease mentalretardation,convulsions,coma,lethargy,coma Decreasedintakeof
branchedchainAA
indiet,
Supplementationof
Thiamine,liver
transplant?
Hypervalinemia Failuretothrive,vomiting,nystagmus,deathwithinoneyearafterbirth
Isovalericacidemia Mentalandmotorretardation,smellofsweatinskinandurine
Intermittentbranched
chainketonuria
neonataldeficiencyinfeeding,anorexia,convulsionsandotherCNSsigns

148. Examples of Aminoaciduria:3a
Aminoaciduria Urinary excretion
of amino acid
Deficient Enzyme/ metabolic defect
Phenylketonuria Phenylalanine Phenylalanine hydroxylase
Tyrosinemia Type II
(Richner- Hanhart syndrome)
Tyrosine Tyrosine transaminase
Neonatal Tyrosinemia Tyrosine p-hydroxy phenylpyruvate dioxygenase
Alkaptonuria Homogentisate Homogentisate oxidase
Tyrosinemia Type I
(Tyrosinosis)
Tyrosine Maleyl acetoacetate isomerase and o
Fumaryl acetoacetate hydroxylase

149. Clinical features and Managementof Aminoaciduria:3b
Aminoaciduria Clinical features Management
Phenylketonuria usually(butnotalways)mentalretardation,
stuntedgrowth,failuretowalkandtalk,
convulsions/seizure,tremors,eczema,fairhair
andcomplexions(hypopigmentation),blueeyes
LowPhenylalanineindiet
andorfeedingsynthetic
aminoacidpreparation,
supplementationof5-
hydroxytryptophan,DOPA
andtetrahydropterin
TyrosinemiaTypeII
(Richner-Hanhartsyndrome)
mentalretardation,Skin(dermatitis)andeye
lesions,disturbed self-coordination
LowPhenylalanineand
Tyrosine
NeonatalTyrosinemia Temporaryconditions Ascorbic acid
Alkaptonuria Ochronosis(Alkaptondepositioninconnective
tissue,bones,nose,earsetc),arthritis
ConsumptionProteindiet,
LowPhenylalanineindiet
TyrosinemiaTypeI(Tyrosinosis) Diarrhea,vomiting,cabbagelikeodor,death
withinoneyearafterbirth
LowPhenylalanine,
Tyrosineandmethionine
indiet