The putative coenzyme B12-dependent methylmalonyl-CoA mutase from potatoes is a phosphatase.

The reported presence of a coenzyme B12-dependent methylmalonyl-CoA mutase in potatoes has been reexamined. The enzyme converting methylmalonyl-CoA was purified to electrophoretic homogeneity. Examination of the reaction product by 1H, 31P NMR and mass spectrometry revealed that it was methylmalonyl-3'-dephospho-CoA. The phosphatase enzyme needs neither coenzyme B12 nor S-adenosylmethionine as a cofactor.