Arachidoyl- and arachidonoyl-CoA elongation mechanism in swine cerebral microsomes.

Long-chain saturated and polyunsaturated fatty acyl-CoA elongations were studied in swine cerebral microsomes. The elongation of endogenous palmitoyl-CoA to stearate was highly active in both cerebral and liver microsomes, whereas those of arachidoyl-CoA (20:0-CoA) and endogenous arachidonoyl-CoA (20:4-CoA) were high in cerebral microsomes, but negligible in liver microsomes. The elongation of 22:4 to 24:4 was also observed in cerebral microsomes. Both NADPH and NADH at 500 microM were effective in elongation of 16:0-, 20:0- and 20:4-CoA, whereas NADPH was more effective in elongation of 22:4 to 24:4 than NADH. The incorporation of deuterium atoms to the elongated product was detected by the technique of mass fragmentography when the NADPH-dependent elongations of 20:0-CoA and 20:4-CoA were performed in 2H2O medium upon cerebral microsomes. The number of incorporated deuterium atoms into 22:0 elongated from 20:0-CoA was mainly two, and that into 22:4 elongated from 20:4-CoA was mainly three. These results indicated that part of hydrogens in elongated arachidoyl- and arachidonoyl-CoA were transferred from NADPH.