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Methylmalonyl -coenzyme A, short- methylmalonyl -CoA, is an organic chemical compound. She is a thioester - from coenzyme A and methylmalonic acid - and a carboxylic acid. In biochemistry and the anion of the carboxylic acid is referred to as methylmalonyl -CoA. The thioester occurs as an intermediate in the degradation of fatty acids with an odd number of carbon atoms as well as certain amino acids. The product formed during the degradation of methylmalonyl -CoA succinyl -CoA formed in the metabolism in the citric acid cycle; reaction with guanosine diphosphate (GDP) and free phosphate is catalyzed by the succinyl-CoA synthetase, and supplies the analog to ATP energy guanosine triphosphate (GTP).

Importance in fatty acid and amino acid metabolism

Methylmalonyl -CoA is produced in the body in the conversion of propionyl-CoA, which is formed of fatty acids having an odd number of carbon atoms in succinyl- CoA, which further react in the citrate cycle. The formation reaction of propionyl CoA is catalyzed by propionyl -CoA carboxylase in a biotin- dependent carboxylation. First, it is produced, the D- enantiomer. The methylmalonyl -CoA racemase catalyzes the isomerization of D- methylmalonyl -CoA to L- methylmalonyl -CoA. This intermediate product is converted by the L- methylmalonyl -CoA to succinyl-CoA mutase. The reaction requires vitamin B12 as a cofactor.

In the degradation of some amino acids such as isoleucine, valine, methionine and threonine also formed propionyl-CoA which is converted via the same pathway as in fatty acids via methylmalonyl -CoA to succinyl -CoA.


Lack of L- methylmalonyl -CoA mutase or significant vitamin B12 deficiency can lead to methylmalonic aciduria, which leads through an accumulation of methylmalonyl -CoA to toxic effects. If left untreated, can lead to serious brain damage or death to the disease within a very short time.