Effect of Methylmalonyl Coenzyme A, a Metabolite Which Accumulates in Vitamin B12 Deficiency, on Fatty Acid Synthesis

We have proposed that the accumulation of methylmalonyl-CoA, which occurs when a deficiency of B12 coenzyme exists, may lead to its incorporation into fatty acids in place of malonyl-CoA. This lead to the production of fatty acids, which are not usually produced and which may be physiologically undesirable. As a first step in the test of this hypothesis, we have examined the effect of methylmalonyl-CoA on fatty acid synthesis in vitro, in rat liver supernatant fractions. It was shown that methylmalonyl-CoA inhibits fatty acid synthesis and is incorporated into fatty acids.