BIOC 3300 Lecture 12: BIOC3300 Lecture 12
10 Mar 2017
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Document Summary
Triacylglycerols: dietary fats (tg or tag: glycerol backbone esterified to 3 fa chains, dietary tag absorbed from intestine, transported in plasma, stored in adipose tissue. Absorption, transport, storage and mobilization of tag involve a series of hydrolysis and re-esterification reactions involving fas. Important sites of tg metabolism: enterocytes, hepatocytes, adipocytes. Major product of tag digestion: 2-monoacylglycerol + 2 ffa. The 2 proteins form a complex in presence of tag and bile salt micelles (cid:314) conformational change in pancreatic lipase to expose lipid-binding surface. Lid of lipase is re-oriented to expose catalytic residues to tag. Release of fa and binding of micellar lipid causes further recruitment of lipase/colipase complexes. Tag is packaged with apolipoprotein to form chylomicrons. Enzymes for tag synthesis: monoacylglycerol acyltransferases (mgat, diacylglycerol acyltransferases (dgat) Level of tag biosynthesis regulated by: availability of cytosolic fatty acyl-coa and glycerol-3 phosphate (from glycolysis)
