5e Chapter26 2003

5e Chapter26 2003 - 2002 2003 by Changwon Kang Chapter 26 Biosynthesis of Membrane Lipids and Steroids A Membrane components triacylglycerols and

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© 2002, 2003 by Changwon Kang Chapter 26 1 Chapter 26: Biosynthesis of Membrane Lipids and Steroids A. Membrane components, triacylglycerols and steroids (1) Three major components of membrane: phospholipids, sphingolipids and cholesterol. (2) Triacylglycerol (TAG) molecules store excess energy for later use. TAG (3) Steroid hormones are made from cholesterol. B. Phosphoglycerides (glycerol-based phospholipids) (1) Chemically, they are derivatives of glycerol [CH 2 OH-CHOH-CH 2 OH]. Biochemically, they are derived from diacylglycerol 3-phosphate (= phosphatidate). [Activated diacylglyceride + alcohol] or [Diacylglyceride + activated alcohol] Glycerol 3-phosphate + 2 Acyl CoA Glycerol phosphate acyltransferase O CO R (Triacylglycerol, TAG) OH (Diacylglycerol, DAG) OPO 3 CMP (CDP-diacylglycerol) CTP [Synthesis from CMP-activated diacylglyceride] [From CDP-activated alcohols in mammals] Serine (amino acid) Inositol (sugar) [HO-CH 2 -CH(COO )-NH 3 + ] C M P C M P Serine CDP-serine Phosphatidyl serine Phosphatidyl inositol A T P + C T P D A G 2 A T P Kinases [HO-CH 2 -CH 2 -NH 3 + ] C O 2 Ethanolamine CDP-ethanolamine Phosphatidyl ethanolamine Phosphatidyl inositol ATP + CTP DAG 4,5-bisphosphate (PIP 2 ) ` Phospholipase C [HO-CH 2 -CH 2 -N(CH 3 ) 3 + ] 3 S A M ( CH 3 ) (p. 404) Choline CDP-choline Phosphatidyl choline DAG + IP 3 ATP + CTP DAG (Inositol triphosphate) (2) Variety of phosphoglycerides Variation on the fatty chains: saturated and unsaturated. Variation on the alcohol-derivative unit 1. an amino acid (eg. serine) 2. a sugar (eg. inositol) 3 . ethanolamine 4. choline [N-trimethylethnolamine] Variation on the linkage at C-1: acyl and ether linkages.
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This note was uploaded on 05/05/2008 for the course BIOL 4094 taught by Professor Bartlett during the Spring '03 term at LSU.

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5e Chapter26 2003 - 2002 2003 by Changwon Kang Chapter 26 Biosynthesis of Membrane Lipids and Steroids A Membrane components triacylglycerols and

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