What is the primary enzyme responsible for breaking down fat?
gastric and pancreatic lipase
what digestion of lipid occurs in the stomach?
gastric lipase cleaves FA from sn-3 leaving a free FA and a diacylglycerol
Where are bile acids made?
In the liver from cholesterol
Explain TG digestion in the small intestine
bile is released by the gallbladder after stimulation by CCK. Trypsin stimulates procolipase to colipase which bind to pancreatic lipase helping it function in the small intestine to cleaves the sn-1 and sn-3 FA.
explain the digestion of phospholipids
trypsin activates phospholipase A2 which cleaves FA at sn-2 leaving a lysophospholipid and a FA
explain the digestion of Cholesterol
cholesteryl esterase (carboxylester lipase) cleaves the FA from the cholesterol leaving a free FA and Cholesterol
What is the role of micelles in lipid absorption?
Micelles allow fats through the unstirred water layer into the intestinal epithelium.
Explain the process of lipid absorption?
Once in the intestinal epithelium the fats bind to transport proteins that bring them to the ER where B48 helps package them into chylomicrons. The chylomicrons then enter the lymph.
What are the three enzymes involved in Lipogenesis?
Acetyl CoA Carboxylase (ACC)
Fatty Acid Synthase (FAS)
Stearoyl CoA Desaturase (SCD)
Explain the role of Acetyl CoA Carboxylase (ACC)
-It is highly regulated: stimulated by Citrate, inhibited by LCFA, Phosphorylation decreases ACC activity
-End product (Malonyl CoA) is important in regulation of β-oxidation.