Methylmalonic acid (MMA) is a dicarboxylic acid that is a C-methylated derivative of malonate. The coenzyme A linked form of methylmalonic acid, methylmalonyl-CoA, is converted into succinyl-CoA by methylmalonyl-CoA mutase, in a reaction that requires vitamin B12 as a cofactor. In this way, it enters the Krebs cycle, and is thus part of one of the anaplerotic reactions.