Methylmalonyl CoA epimerase [SEP] found in taxon
Methylmalonyl CoA epimerase
Methylmalonyl CoA epimerase (, "methylmalonyl-CoA racemase", "methylmalonyl coenzyme A racemase", "DL-methylmalonyl-CoA racemase", "2-methyl-3-oxopropanoyl-CoA 2-epimerase [incorrect]") is an enzyme involved in fatty acid catabolism that is encoded in human by the "MCEE" gene located on chromosome 2. It is routinely and incorrectly labeled as "methylmalonyl-CoA racemase". It is not a racemase because the CoA moiety has 5 other stereocenters. 
Structure.
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first carboxylated to ("S")-methylmalonyl-CoA by the enzyme Propionyl-CoA carboxylase. Methylmalonyl CoA epimerase then catalyzes the rearrangement of ("S")-methylmalonyl-CoA to the ("R") form in a reaction that uses a vitamin B12 cofactor and a resonance-stabilized carbanion intermediate. The ("R")-methylmalonyl-CoA is then converted to succinyl-CoA in a reaction catalyzed by methylmalonyl-CoA mutase.
Acting as a general base, the enzyme abstracts a proton from the β-carbon of ("R")-methylmalonyl-CoA.