Factors Involved in Fatty Acyl CoA Desaturation by Fungal Microsomes

摘要: 1 Microsomes were prepared from strain 74a Neurospora crassa mycelium. Gas-liquid chromatographic analysis indicated that approximately 80 % of the microsomal fatty acids contained 18 carbon atoms; 90% 18-carbon unsaturated, and these linoleic acid was major component. 2 Microsomes suspended in 0.1 M phosphate buffer pH 7.1 could desaturate both [1-14C]-stearyl CoA [1-14C]oleyl CoA; however, latter Δ 12 desaturation always an order magnitude slower than 9 as assayed by radiogaschromatography. Attempts to solubilize desaturase activity unsuccessful. 3 Oxygen a nucleotide required for desaturation. The rate higher with NADH NADPH, NADP almost effective NADPH. presence NAD slow, no detectable at occurred this oxidized nucleotide. 4 Mycelial microsomes used test hypothesis phospholipids are intermediates Microsomes incubated 30°C 14C-labeled acyl substrates absence reduced nucleotides, then washed remove unused CoA, and, finally, 30° C NADH. No stearyl under conditions; [14C]oleyl-labeled converted linoleyl phospholipid normal rate. 5 Stearyl rapidly oleyl free stearic NADH. 6 Oleyl much more incorporated into hydrolyzed acid, even nucleotide. 7 Stearyl all tightly, but not covalently, bound microsomes. 8 The data rule out possibility being intermediate However, experiments consistent phospholipid's conversion phospholipid. 9 The do establish whether or direct desaturases fungal microsomes.