enzymes-
-definition,types and classification of enzymes.
-coenzymes,specificity of enzymes ,isoenzymes,enzyme kinetics including factors affecting velocity of enzymes catalysed reaction.enzyme inhibition
2. TOPICS TO BE
DISCUSSED
What is biochemistry?
Objectives,scope and importance of biochemistry and
its relation to
nutrition
ENZYMES-
Definition,types and classification
Coenzymes,specificity of enzymes,isoenzymes,enzyme
kinetics including factors affecting velocity of enzymes
catalysed reaction.Enzyme inhibition
NUCLEIC ACIDS-
Classification,composition and function of nucleic acids
Structure and properties of nucleosides,nucleotides
Genetic code.
3. BIOCHEMISTRY
“Biochemistry has become the foundation for
understanding all biological processes. It has
provided explanations for the causes of many
diseases in humans, animals and plants.”
“Biochemistry is a study of the chemical
substances & processes that occur in plants,
animals & microorganisms & of the changes
they undergo during development & life.”
4. Biochemistry is both life science and a chemical science
- it explores the chemistry of living organisms and the
molecular basis for the changes occurring in living cells.
It uses the methods of chemistry, physics, molecular
biology, and immunology to study the structure and
behavior of the complex molecules found in biological
material and the ways these molecules interact to form
cells, tissues, and whole organisms
5. OBJECTIVES OF
BIOCHEMISTRY
Study the structures and functions of biomolecules like
carbohydrate, lipids, proteins minerals and DNA.
Focuses on techniques used to control diseases, abnormal
deficiency and treatment of deficiencies.
Understand the dynamic changes of cellular systems and
corresponding need of nutrients.
They act as catalyst agent.
Metabolic abnormalities can be studied by knowledge of
biochemistry.
Study of the energy transformations in living cells,
organisms is another objective of study of biochemistry.
6. IMPORTANCE OF
BIOCHEMISTRY
Biochemistry is thriving right now. In recent years it has
become the most critical area of science.
It combines the core of biology and chemistry, which
opens a new door for research from the very ground up.
Biochemistry helps us understand the medical
conditions such as diabetes, jaundice, rickets, etc. with
its research, and scientists are now able to find a
medication that can cure them or put them in control.
Biochemistry can help us find a way to decompose our
waste without harming nature successfully.
This field can also do wonders in the coming years and
make us live on other planets as we study the chemical
changes that happen on other planets such as mars.
7. SCOPES OF BIOCHEMISTRY
Biochemistry play an important role in various
fields such as; in clinical medicine,
pharmacology, biotechnology, agriculture,
horticulture, forestry, nursing, pathology, in
physiology, and also in microbiology.
BIOCHEMISTRY IN MEDICINE
• Physiology
• Pathology
• Nursing and diagnosis
9. SCOPE OF
BIOCHEMISTRY
BIOCHEMISTRY IN NUTRITION
• Food chemistry gives an idea of what we eat. The
nutrients value of food material can also be determined
by biochemical tests.
• Nutritional biochemical therapy saves lives, reduces
morbidity, improves health outcomes, and reduces
healthcare costs and patients.
11. OTHER SCOPES
• Biotechnologist
• Research Scientist
• Clinical Scientist
• Research Associates
• Chemist Microbiologist
• Biomedical Scientist
• Pharmacologist Laboratory Technician
• Lecturer in an Educational institution
12. RELATIONSHIP WITH
NUTRITION
Nutrition is the study of nutrients in food, how the body uses
them, and the relationship between diet, health, and disease.
Nutritional biochemistry deals with various studies in
nutrients, food constituents and their function regarding
humans and other mammals, nutritional biochemistry
specifically focuses on nutrient chemical components, and
how they function biochemically, physiologically,
metabolically, as well as their impact on disease.
13.
14. Definition
“Enzymes can be defined as biological polymers that
catalyze biochemical reactions.”
• Enzymes are nitrogenous organic molecules
produced by living organisms such as plants and
animals. A long chain of one or more amino acids
is connected together using amide or peptide
bonds to make them.
• Enzymes have a specific method of action (Lock-
and-Key mechanism and Enzyme Fit Hypothesis).
15. STRUCTURE OF ENZYMES
• Enzymes are proteins that are made up of
several polypeptide chains, also known as
amino acids, that have been folded and coiled
numerous times.
• They have linear chains of amino acids in
three-dimensional structures.
• The enzyme’s catalytic activity is determined
by the amino acid sequence. Only a small
portion of an enzyme’s structure participates in
catalysis and is located around the binding
sites.
• They have separate sites; the active site of an
enzyme is made up of the catalytic and binding
sites.
17. 1. Oxidoreductases
Catalyze oxidation/reduction reactions
Oxidation is the loss of electronsor an
increase in the oxidation state of an atom,
an ion, or of certain atoms in a molecule.
Reduction is the gain of electrons or a
decrease in the oxidation state of an atom,
an ion, or of certain atoms in a molecule.
Eg. Alcohol dehydrogenase
Cytochrome oxidase
Amino acid oxidases
18. 2. Transferases
• Involved in transfer of functional groups between molecules
Eg. :-
➢Hexokinase
➢Transaminases
➢Phosphorylase
3. Hydrolases
• Break bonds by adding H2O
Eg:-
Lipase (triacylglycerol acyl hydrolase)
Choline esterase
Acid and alkaline phosphatase
Pepsin
Urease
20. 6. Ligases
• Join molecules with new bonds Eg:-
Glutamine synthetase
Succinate thiokinase
Acetyl CoA carboxylase
21. Examples of Enzymes
Beverages
• Alcoholic beverages generated by fermentation vary a lot
based on many factors. Based on the type of the plant’s
product, which is to be used and the type of enzyme
applied, the fermented product varies.
• For example, grapes, honey, hops, wheat, cassava roots,
and potatoes depending upon the materials available.
Beer, wines and other drinks are produced from plant
fermentation.
Food Products
• Bread can be considered as the finest example of
fermentation in our everyday life.
• A small proportion of yeast and sugar is mixed with the
batter for making bread. Then one can observe that the
bread gets puffed up as a result of fermentation of the
sugar by the enzyme action in yeast, which leads to the
formation of carbon dioxide gas. This process gives the
texture to the bread, which would be missing in the
absence of the fermentation process.
22. Drug Action
Enzyme action can be inhibited or promoted by
the use of drugs which tend to work around the
active sites of enzymes.
Mechanism of Enzyme Reaction
Enzymes are said to possess an active site. The
active site is a part of the molecule that has a
definite shape and the functional group for the
binding of reactant molecules. The molecule that
binds to the enzyme is referred to as the substrate
group. The substrate and the enzyme form an
intermediate reaction with low activation energy
without any catalysts.
24. Action and Nature of Enzymes
• The enzyme action basically happens in two
steps:
• Step1: Combining of enzyme and the
reactant/substrate.
• E+S → [ES]
• Step 2: Disintegration of the complex
molecule to give the product.
• [ES]→E+P
• Thus, the whole catalyst action of enzymes
is summarized as:
• E + S → [ES] → [EP] → E + P
26. Factors Affecting Enzyme Activity
• The conditions of the reaction have a great impact
on the activity of the enzymes. Enzymes are
particular about the optimum conditions provided
for the reactions such as temperature, pH,
alteration in substrate concentration, etc.
27. Active site
Enzymatic catalysis depends upon the activity of
amino acid side chains assembled in the active
centre. Enzymes bind the substrate into a region of
the active site in an intermediate conformation.
Temperature and pH
Enzymes require an optimum temperature and pH
for their action. The temperature or pH at which a
compound shows its maximum activity is called
optimum temperature or optimum pH,
respectively. As mentioned earlier, enzymes
are protein compounds. A temperature or pH more
than optimum may alter the molecular structure
of the enzymes. Generally, an optimum pH for
enzymes is considered to be ranging between 5
and 7.
28. • Optimum T°
• The greatest number of molecular collisions
• human enzymes = 35°- 40°C
• body temp = 37°C
• Heat: increase beyond optimum T°
• The increased energy level of molecule disrupts bonds in
enzyme & between enzyme & substrate H, ionic = weak
bonds
• Denaturation = lose 3D shape (3° structure)
• Cold: decrease T°
• Molecules move slower decrease collisions between
enzyme & substrate
30. ENZYME INHIBITION
Enzyme inhibitor is defined as a substance which
binds with the enzyme and brings about a
decrease in catalyrtc activity of that enzyme. The
inhibitor may be organic or inorganic in nature.
There are three broad categories of enzyme
inhibition
• 1 . Reversible inhibition.
• 2. Irreversible inhibition.
• 3. Allosteric inhibition.
31. 1. Reversible inhibition
The inhibiior binds non-covalently with enzyme and
the enzyme inhibition can be reversed if the
inhibitor is removed. The reversible inhibition is
further sub-divided into
l. Competitive inhibition
ll. Non-competitive inhibition
34. 2. lrreversible inhibition
Inhibitor binds covalently(strong)with the enzyme
irreversibly
Soit can’t dissociate from the enzyme
Inhibitor cause conformation change at active site
of the E –destroying their capacity to function as
catalysts
Enzyme activity is not regained on dialysis/by
increasing the conc.of S
A variety of poisons,such as iodoacetate,OP
poisoning and oxidizing agents act as irreversible
inhibition
35. In terms of kinetics –irreversible is similor to non
competitive inhibition Vmax– Decreased
Km– No change
36. Suicide Inhibition
Specialized form of irreversible inhibition
Also known as mechanism based inactivation
I makes use of all enzyme’s own reaction
mechanism to inactivate it
Inhibitor(structural analog) is converted to a more
effective inhibitor with the help of the E to be
inhibited
E literally commits suicide-they utilize normal E
mechanism to inactivate the E.
37. 3. Allosteric inhibition
Some E possess additional site other than the
active siete called as Allosteric sites,E –AllostericE.
They are unique site on protein molecule
Allosteric effectors–substances bind of Allosteric
site & regulate E activity
Positive Allosteric effectors-E activity is increased
Negative Allostric effectors-E activity is decreased
Allostric enzyme-sigmoidal curve
38. ENZYME SPECIFICITY
Enzymes are highly specific in their action when
compared with the chemical catalysts. The
occurrence of thousands of enzymes in the
biological system might be due to the specific
nature of enzymes.
39. COENZYME
The non-protein, organic, Iow molecular weight
and dialysable substance associated with enzyme
function is known as coenzyme.
The functional enzyme is referred to as
holoenzyme which is made up of a protein part
(apoenzyme) and a non-protein part (coenzyme).
Coenzymes are often regarded as the second
substrates or co-substrafes, since thev have
affinity with the enzyme comparable with that of
the substrate.
the coenzymes are the derivatives of water
soluble B-complex vitamins. In fact, the
biochemical functions of B-complex vitamins are
exerted through their respective coenzyme.
40. LOCK- AND- KEY MODEL
• In the lock and key model of enzyme action:
-the active site has a rigid shap.
-only substrate with the matching shape can fit.
-the substrate is a key that fits the lock of the active
site.
-the amino acid R group of enzymes hepl to mediat
interaction of active site and substrate.
• This is an older model,however and does not work
for all enzymes.
Limitations
• Generally applicable for enzymes that
work on single type of substrate.
• It indicates the active site as a rigid
shape but it is actually flexible.
• Rigid shape is insensitive to enviroment
modification for substrate binding.
41. INDUCED FIT MODEL
• In the induced fit model of enzyme action:
-the active site is flexible,not rigid.
-the shape of the enzyme,active site and substrate
adjust to maximize the fit,which improves catalysis.
-there is greater range of substrate specificity
• This model is more consistant with a wider range
of enzymes.
Advantages:
Support enzymes which can act on different
Substrate of different conformations.
Enhance fidelity of molecular recognition
In presence of competitor via conformational
Proof reading.
Much accepted as enzymes are not rigid and
Different conditions promote differential interactions.
If it was rigid all the actions were same att always.
43. HOW ARE THEY FORMED?
• formed due to homologous or recombination of
genepair.
• i.e.during gene duplication the duplicate code is
retained which leads to formation of isoenzymes.
44. Isoenzymes existence’s explanation
1.lsoenzymes synthesized from different
genes e.g. malate dehydrogenase of cytosol
is different from that found in mitochondria.
2. Oligomeric enzymes consisting of more
than one type of subunits e.g. lactate
dehydrogenase and creatine
phosphokinase.
3. Isoenzyme may be active as monomer or
oligomer e.g. glutamate dehydrogenase.
4. Differences in carbohydrate content may
be responsible for isoenzymes e.g. alkaline
phosphatase.
45. Isoenzymes of Lactate Dehydrogenase
• Tetramer with foursubunits
• Subunits may be either H or M polypeptide
chain
• Due to different combination of H & M
5 isoforms are there
Isoform subunits Location
LDH1 H4 Heart
LDH2 H3M1 RBC
LDH3 H2M2 Brain
LDH4 H1M3 Liver
LDH5 M4 Muscle
Function:-convert locatate to pyruvate.
46. Isoenzymes of creatine phosphokinase
• Dimer
• Contain M and B subunits
• Has 3 isoforms
Isoform subunits Location
CPK1 MM Muscle
CPK2 MB Heart
CPK3 BB Brain
Function:-converts creatine phosphatase to creation.
47. Alkaline phosphatase
• Has 6 isoenzymes
• Monomer
• Isoenzymes are due to different in
carbohydrate content.
1. Alpha1 ALP -epithelial cells of biliary
canaliculi
2. Alpha2 ht labile -hepatic cells
3. Alpha2 ht stable -placenta
4. Pre beta ALP -bone
5. Gamma ALP -intestinal cells
6. Leukocyte ALP
48. ENZYME PATTERN IN
DISEASES
• Enzymes in myocardial infarction
Creatine phosphokinase
Asparate transaminase
Lactate dehydrogenase
Cardiac troponins
49. • Enzymes in liver diseases
• Enzymes in muscle diseases
• Enzymes in cancers
50. ENYME KINEETICS-FACTORS
• The catalytic properties of enzymes,and
consequently their activity,are influenced by
numerous factors.
• These factors include
Physical quantities(temperature,pressure)
The chemical properties of the solution (pH
vatue,ionic strength)
The concentrations of the relevent
subntrates,cofactors and inhibitors.
51. pH dependency of enzyme activity
• Eeffect of enzymes is strongly dependent on the Ph
• A ctivity is plotted against pH,a bell-shapped curve is
usually obtained
• Bell shape of the activity-pH profile results from the fact
that amino acid residues with ionizable groups in the side
chain are essential for catalysis.
pH dependency of enzyme
activity
• A basic group B(pKa=8)which has to be protonated in order
to become active.
• A second acidic amino acid AH(pKa=6),which is only active
in a dissociated state.
• At the optimum pH of 7,around 90%of both groups are
present in the active form.
• At higher and lower values,one or the other of the groups
52. Temperature dependency of enzyme
activity
• The pemperature dependency of enzymatic activity is
usually asymmetric.
• With increasing temperature,the increased thermal
movement of the molecules initially leads to a rate
acceleration.
• At a certain temperature the enzyme then becomes
unstable and its activity is lost within a narrow
temperature difference as a result of denaturation.
53.
54. HISTORIC RESUME FRIEDRICH
MIESCHER IN 1869
• Isolated what he called nuclein from the nuclei
of pus cells.
• Nuclein was shown to have acidic
properties,hemce it became called nucleic
acid.
NUCLEIC ACID
• Nucleicc asid aree polymers that consist of nucleotide
residues.
• Located in nuclei of cell.
• Hereditary determinants of living organisms
• Elemental composition-
carbon,hydrogen,oxygen,nitrogen and phosphorus.
56. The Distribution of nucleic acids in the
eukaryotic cell
• DNA is found in the nucleus
with small amounts in mitochondria and chloroplasts
• RNA is found throughtout the cell
NUCLEIC ACID
STRUCTURE
• Nucleic acids are polynucleotides
• Their building blocks are nucleotides
57. NUCLEOTIDES
• Energy rich compounds that drive meta bolic process in
cell
• Serve as chemical signals,key links in cellilar systems that
respond to hormones and other extracellular stimuli
• Structural component of an of enzyme cofactor and
metabollic intermediate
• Each nucleotide is formed by 3 units-
PHOSPHATE,SUGAR,NITROGENUOS BASE
58. NUCLEOSIDES
When ribose or 2-deoxyribose is
combinedwith purine and pyramidine base
Nucleoside is formed.
59. Properties of Nucleotides
Properties of purine bases
• Sparingly soluble in water
• Absorb light in UV region at 260 nm. (detection &
quantitation of nucleotides)
• Capable of forming hydrogen bond
• Aromatic base atoms numbered 1 to 9
• Purine ring is formed by fusion of pyrimidine ring
with imidazole ring.
• Numbering is anticlockwise.
Adenine : Chemically it is 6-aminopurine
Guanine : Chemically it is 2-amino,6-oxy purine
Can be present as lactam & lactim form
60. Properties of pyrimidine bases
• Sparingly soluble in water
• Absorb light in UV region at 260 nm. (detection &
quantitation of nucleotides)
• Capable of forming hydrogen bond
• Aromatic base atoms numbered 1 to 9
• Purine ring is formed by fusion of pyrimidine ring
with imidazole ring.
• Numbering is anticlockwise.
• Adenine : Chemically it is 6-aminopurine
• Guanine : Chemically it is 2-amino,6-oxy purine
Can be present as lactam & lactim form
61. Properties of pyrimidine bases
• Soluble at body pH
• Also absorb UV light at 260 nm
• Capable of forming hydrogen bond
• Aromatic base atoms are numbered 1 to 6 for
pyrimidine.
• Atoms or group attached to base atoms have same
number as the ring atom to which they are bonded.
• Cytosine: Chemically is 2-oxy ,4-amino pyrimidine
Exist both lactam or lactim form
• Thymine: Chemically is 2,4 dioxy ,5-methyl pyrimidine
• Occurs only in DNA
• Uracil: Chemically is 2,4 dioxy pyrimidine
Found only in RNA
62. Properties of Pentose Sugars
• A pentose is a monosaccharide with five carbon atoms.
• Ribose is the most common pentose with one oxygen
atom attached to each carbon atom.
• Deoxyribose sugar is derived from the sugar ribose by loss
of an oxygen atom.
• The aldehyde functional group in the carbohydrates react
with neighbouring hydroxyl functional groups to
form intramolecular hemiacetals.
• The resulting ring structure is related to furan, and is
termed a furanose.
• The ring spontaneously opens and closes, allowing rotation
to occur about the bond between the carbonyl group and
the neighboring carbon atom yielding two distinct
configurations (α and β). This process is
termed mutarotation.
64. Classification of Nucleosides
1. Adenosine nucleotides: ATP, ADP, AMP, Cyclic
AMP
2. Guanosine nucleotides: GTP, GDP, GMP, Cyclic
GMP
3. Cytidine nucleotides: CTP, CDP, CMP and
certain deoxy CDP derivatives of glucose,
choline and ethanolamine
4. Uridine nucleotides: UDP
5. Miscellaneous : PAPS (active sulphate), SAM
(active methionine), certain coenzymes like
NAD+, FAD, FMN, Cobamide coenzyme, CoA
65. GENETIC CODE
The genetic code can be defined as the set
of certain rules using which the living cells
translate the information encoded within
genetic material (DNA or mRNA sequences).
The ribosomes are responsible to
accomplish the process of translation. They
link the amino acids in an mRNA-specified
(messenger RNA) order using tRNA (transfer
RNA ) molecules to carry amino acids and
to read the mRNA three nucleotides at a
time.
67. A key point of the genetic code is its universal
nature. This indicates that virtually all species with
minor exceptions use the genetic code for protein
synthesis.
In other words, genetic code is defined as the
nucleotide sequence of the base on DNA which is
translated into a sequence of amino acids of the
protein to be synthesized.
Properties of Genetic Code
• Triplet code
• Non-ambiguous and Universal
• Degenerate code
• Nonoverlapping code
• Commaless
• Start and Stop Codons
• Polarity
68. Triplet code
The four bases of nucleotide i.e, (A, G, C, and U) are used
to produce three-base codons. The 64 codons involve
sense codons (that specify amino acids). Hence, there are
64 codons for 20 amino acids since every codon for one
amino acid means that there exist more than code for the
same amino acid.
Commaless code
No room for punctuation in between which indicates that
every codon is adjacent to the previous one without any
nucleotides between them.
Nonoverlapping code
The code is read sequentially in a group of three and a
nucleotide which becomes a part of triplet never becomes
part of the next triplet.
• For example
• 5’-UCU-3’ codes for Serine
• 5’-AUG-3’ codes for methionine
69. Polarity
Each triplet is read from 5’ → 3’ direction and the
beginning base is 5’ followed by the base in the middle
then the last base which is 3’. This implies that the codons
have a fixed polarity and if the codon is read in the reverse
direction, the base sequence of the codon would reverse
and would specify two different proteins.
Degenerate code
• Every amino acid except tryptophan (UGG) and methionine
(AUG) is coded by various codons, i.e, a few codons are
synonyms and this aspect is known as the degeneracy of
genetic code. For instance, UGA codes for tryptophan in
yeast mitochondria.
• Start and Stop Codons
• Generally, AUG codon is the initiating or start codon. The
polypeptide chain starts either with eukaryotes
(methionine) or prokaryotes (N- formylmethionine).
• On the other hand, UAG, UAA and UGA are called as
termination codons or stop codons. These are not read by
any tRNA molecules and they never code for any amino
acids.
70. Non-ambiguous and Universal
The genetic code is non-ambiguous which means a
specificcodon will only code for a particular amino acid. Also,
the same genetic code is seen valid for all the organisms i.e.
they are universal.
