Biochemistry - Digestion of Lipids

1. V.S.Rashmi Priyem
ULTRA’s BEST Dental Science College

2. DIGESTIONOF LIPIDS
•Digestion In Stomach
•Lingual Lipase
•Gastric Lipase
•Digestion In Intestines
•Emulsification
•Bile Salts
•Factors
•Lipolytic Enzymes In
Intestines
•DigestionOfTriglycerides
• Pancreatic Lipase
•Isomerase
•Cholesterol Ester
•Co-lipase
Rashmi Priyem Saravanan

3.  The Major Dietary Lipids are
 Triacyl Glycerol
 Cholesterol
 Phospholipids
 Average Normal Indian Diet contains
about 20-30 g of Lipids per Day
Rashmi Priyem Saravanan

4.  The Lingual Lipase from the Mouth enters
Stomach along with the food
 It has an Optimum pH of 2.5-5
 The Enzyme continues to be Active in the
Stomach
 Acts on Short ChainTriglycerides (SCT)
 SCTs are present in Milk, Butter and Ghee
 The action of Lingual Lipase is observed to be
More Significant in the Newborn Infants
Rashmi Priyem Saravanan

5.  Gastric Lipase is Acid Stable, with an
Optimum pH around 5.4
 Secreted by Chief ells, the Secretion is
Stimulated by Gastrin
Rashmi Priyem Saravanan

6.  Emulsification is a Prerequisite for Digestion of
Lipids
 The Lipids are Dispersed into Smaller Droplets-
 SurfaceTension is Reduced
 Surface Area of Droplets is Increased
 This Process is Favoured by:
 1. Bile Salts (DetergentAction)
 2. Peristalsis (Mechanical Mixing)
 3. Phospholipids
Rashmi Priyem Saravanan

7.  The Bile Salts present in the Bile (Sodium
glycocholate and Sodium taurocholate)
 Lower SurfaceTension
 EmulsifyThe Fat Droplets.
 The Emulsification IncreasesThe Surface
Area of the particles for EnhancedActivity of
Enzymes.
Rashmi Priyem Saravanan

8.  1. Pancreatic lipase with Co-lipase
 2. Cholesterol esterase
 3. PhospholipaseA2.
Rashmi Priyem Saravanan

9.  The Bile (pH 7.7) entering the Duodenum
serves to Neutralise the AcidChyme from the
Stomach and provides a pH Favorable for the
action of Pancreatic Enzymes.
Rashmi Priyem Saravanan

10. Rashmi Priyem Saravanan

11.  1. Pancreatic Lipase can easily Hydrolyse the
FattyAcids Esterified to the 1st and 3rd
Carbon Atoms of Glycerol forming 2-
Monoacylglycerol andTwo Molecules of Fatty
Acid
Rashmi Priyem Saravanan

12.  2.Then an Isomerase Shifts the Ester Bond
from Position 2 to 1
 The Bond in the 1st Position is then
Hydrolysed by the Lipase to form Free
Glycerol and Fatty acid
Rashmi Priyem Saravanan

13.  3. Cholesterol Ester may be Hydrolysed to
Free Cholesterol and FattyAcid
 The action of PhospholipaseA2 produces
Lysophospholipid and a FattyAcid
Rashmi Priyem Saravanan

14.  The Co-lipase is secreted by the Pancreas as
an InactiveZymogen
 It is activated byTrypsin
Rashmi Priyem Saravanan