Biochemical nature of pyruvate dehydrogenase complex in the patient with primary lactic acidaemia

The biochemical nature of the pyruvate dehydrogenase complex (PDHC) in muscle was studied in a patient with pyruvate dehydrogenase complex deficiency. The enzyme activity was approximately 30% of the control level and the apparent Km value of the enzyme was similar to the control value. The immunoblot pattern of each subunit protein, E1 alpha, E1 beta, the component X, E2 and E3, was comparable to that of the control on both one- and two-dimensional electrophoresis, the staining of each subunit protein being reduced in intensity, corresponding to the reduced enzyme activity. The enzyme deficiency is likely to be quantitative rather than qualitative, although the actual mechanism is unknown.