Methylmalonyl-CoA mutase (EC:5.4.99.2) (MCM) PMID:1975493 is an adenosylcobalamin (vitamin B12) dependent enzyme that catalyzes the isomerization between methylmalonyl-CoA and succinyl-CoA. MCM is involved in various catabolic or biosynthetic pathways; for example in man it is involved in the degradation of several amino acids, odd-chain fatty acids and cholesterol via propionyl-CoA to the tricarboxylic acid cycle; while in some bacteria it is involved in the synthesis of propionate from tricarboxylic acid-cycle intermediates.

Deficiency of MCM in man causes an often fatal disorder of organic acid metabolism termed methylmalonic acidemia. The sequences of eukaryotic and prokaryotic MCM are rather well conserved. In eukaryotes MCM is located in the mitochondrial matrix and is a homodimer of a polypeptide chain of about 710 amino acids. In bacteria MCM is a dimer of two non-identical, yet structurally related chains. This family also includes an Escherichia coli protein (gene sbm) whose function is not yet known.

A small degree of similarity is said PMID:2197274 to exist between MCM and the large subunit of the adenosylcobalamin-dependent enzyme ethanolamine ammonia-lyase, but this similarity is so weak that these two type of enzymes can not be detected by a single pattern.

INTERPRO:IPR006099