A radio-HPLC assay for the measurement of methylmalonyl-CoA mutase

Previously-described assays of mutase activity use either [14C]methylmalonyl-CoA or propionyl-CoA and [14C]bicarbonate and involve the separation of radiolabelled methylmalonic acid and succinic acids. These methods suffer from a lack of sensitivity and are laborious. The gas chromatographic assay used for the measurement of leucocyte mutase has been shown to distinguish patients from the mut and cbl mutant groups, but has not found widespread use because it is extremely time-consuming. The authors describe here a new, rapid assay for methylmalonyl-CoA mutase activity performed under conditions of saturating coenzyme. The assay was used to investigate mutase activity in a number of children with methylmalonic acidaemia and to determine the co-operativity index for the interaction of adenosylcobalmin with the leukocyte apomutase. (Auth.)