Effect of malonyl-CoA on delta 6 desaturation activity of rat liver microsomes.

The effect of malonyl-CoA on linoleic acid desaturation and elongation reactions of rat liver microsomes was studied. Under strict desaturation conditions, the in vitro microsomal conversion of linoleic acid to gamma-linolenic acid is time-dependent. When malonyl-CoA was added to the aforementioned incubation medium, linoleic acid was desaturated to gamma-linolenic acid and elongated to its higher homologues. Under these conditions, delta 6 desaturation activity, calculated by adding gamma-18:3, 20:3 and 20:4 acids, was neither inhibited nor activated by malonyl-CoA. These results indicate that the elongation of gamma-linolenyl-CoA coupled to the desaturation of linoleic acid did not modify delta 6 desaturase activity.