1 - Digestion and absorption of lipids

What enzymes are involved in digestion and absorption of lipids?

1. Lingual Lipase

2. Gastric Lipase 

3. Pancreatic Lipases

Lingual Lipase

Hydrolyzes ester bonds in triacylglycerols

Acidic pH optimum, but saliva is basic = Not very efficient

Gastric Lipase

Hydrolyzes ester bonds in Triacylglycerols

Acidic pH optimum, more efficient since the stomach is acidic.

Pancreatic Lipases

Hydrolyzes ester bonds of triacylglycerols

What other components are necessary?

• Phospholipase A1, A2, C, and D

• Bile

• Ceramidase

• Glycosidases

Phospholipase A1, A2, C, and D

hydrolyze Ester bonds in phosphoglycerides 

Bile

It emulsifies lipids into tiny droplets to increase the surface area for enzyme action. Product of cholesterol.

Why is emulsification necessary for lipid digestion?

Lipid-digesting enzymes are water-soluble and act at the lipid/water interface.

Ceramidase

In small intestine released from pancreas

Hydrolyzes the amide bond in sphingolipids

Glycosidases

Small intestine

Hydrolyze glycosidic bonds in sphingolipids

Products of digestion and absorption of lipids

Fatty acids, monoacylglycerols, glycerol, sphingosine, polar alcohols, and monosaccharides

Where are the products absorbed?

Absorbed into the epithelium of the small intestine by diffusion and secondary active transport