Deficiency of the Pyruvate Dehydrogenase Component in Pyruvate Dehydrogenase Complex-deficient Human Fibroblasts

A previously reported deficiency of total pyruvate dehydrogenase complex activity is further characterized. Dihydrolipoyl transacetylase (E2) and lipoamide dehydrogenase (E3) activities in the patient's fibroblasts were normal. Pyruvate dehydrogenase activity (El) was 33% ofthat in fibroblasts from an age-matched control. The amounts of each of the components of pyruvate dehydrogenase complex were analyzed using an immunoblot technique and specific antibodies. Levels of components E2 and E3 were the same in fibroblasts from the patient and control, confirming the activity measurements. However, the levels of Ela and Elft were reduced markedly in fibroblasts from the patient. Thus, impairment in the pyruvate dehydrogenase complex activity was due to a reduction in the amount ofthe El component of the complex.