title: Membrane-bound phospholipid desaturases.
abstract: This review covers studies on membrane-bound phospholipid desaturases in yeast and rat liver carried out in this laboratory. In yeast the desaturase system was shown to effect the direct desaturation of dioleoyl-lecithin to dilinoleoyl-lecithin. In rat liver the desaturase was capable of converting 2-eicosatrienoyl-lecithin to 2-arachidonoyl-lecithin. Both systems required reduced pyridine nucleotides, O2 and cytochrome b5. Eicosatrienoyl-lecithin desaturase along with eicosatrienoyl-CoA desaturase of rat liver microsomes was solubilized with detergents and purified 7-8-fold from the microsomal pellets. Both activities were reconstituted in the presence of deoxycholate on addition of the other components of the cytochrome b5-electron transport chain (cytochrome b5 and NADH-cytochrome b5 reductase) to the solubilized desaturase; addition of lecithin further stimulated the activities. The demonstration of desaturation of eicosatrienoyl-lecithin by a solubilized and partially purified desaturase provides strong evidence for the direct desaturation of the lecithin substrate without prior conversion to the acyl-CoA thiolester.
mesh_terms: D000214:Acyl Coenzyme A / Q000378:metabolism; D000818:Animals; D002175:Candida / Q000201:enzymology; D003580:Cytochromes / Q000378:metabolism; D044943:Fatty Acid Desaturases / Q000378:metabolism*; D007425:Intracellular Membranes / Q000201:enzymology*; D007700:Kinetics; D008861:Microsomes / Q000201:enzymology; D008862:Microsomes, Liver / Q000201:enzymology; D009243:NAD / Q000494:pharmacology; D010100:Oxygen; D010713:Phosphatidylcholines / Q000378:metabolism; D010743:Phospholipids; D051381:Rats; D013217:Starvation; D013379:Substrate Specificity
chemical_list: D000214:Acyl Coenzyme A; D003580:Cytochromes; D010713:Phosphatidylcholines; D010743:Phospholipids; D009243:NAD; C022369:phospholipid desaturase; D044943:Fatty Acid Desaturases; D010100:Oxygen