An investigation into the role of malonyl coenzyme A in isoprenoid biosynthesis

Abstract

[14C]malonyl CoA was incorporated into isoprenoids by cell free yeast preparations, by preparations from pigeon and rat liver, and by Hevea brasiliensis latex. In agreement with previous reports the incorporation of acetyl CoA into isoprenoids was not inhibited by avidin and was not stimulated by HCO3-. In a cell free yeast preparation addition of HCO3- stimulated the formation of fatty acids from acetyl CoA and decreased the incorporation into unsaponifiable lipids. The labelling patterns of β hydroxy β methylglutaryl CoA formed from [2 14C] and [1,3 14C]malonyl CoA in rat and pigeon liver preparations were those that would be expected if malonyl CoA underwent decarboxylation to acetyl CoA before incorporation. The labelling pattern of ergosterol formed by cell free yeast preparations from [2 14C]malonyl CoA was also consistent with decarboxylation of malonyl CoA before incorporation. The incorporation of [2 14C]malonyl CoA into mevalonate by rat liver preparations was related to the malonyl CoA decarboxylase activity present in the preparation.