[Biosynthesis of fatty acids in mouse brain mitochondria in the presence of malonyl-CoA or acetyl-CoA].

Incorporation of malonyl-CoA or acetyl-CoA is studied in mouse brain mitochondrial fatty acids. Rupture of mitochondria is necessary ; Triton X-100 gives the best result. Other detergents or sonication are of lesser efficiency. Cofactor requirements have been studied : NADH and NADPH have been tested ; ATP increases biosynthesis and CoA causes an inhibition. Two systems of biosynthesis are involved : -- One is a de novo system using malonyl-CoA. Malonyl-CoA alone is incorporated and synthesizes mainly C16, indicating the existence of a malonly-CoA decarboxylase although elongation of short chain fatty acids cannot be excluded. Addition of acetyl-CoA increases the biosynthesis and palmityl-CoA when added causes an inhibition. -- The other system, using acetyl-CoA, elongates exogenous palmityl-CoA ; endogenous acyl-CoAs are not elongated by acetyl-CoA. All these results are confirmed by radiogas chromatographic studies of the reactions products.