An NADH-linked spectrophotometric assay for pyruvate dehydrogenase complex in crude tissue homogenates

A spectrophotometric assay for the pyruvate dehydrogenase complex has been developed, which measures NADH production by coupling it to the reduction of a tetrazolium dye via an intermediate electron carrier. The procedure uses only commercial reagents. Dependence on pyruvate, coenzyme A, and NAD is complete, and activities are comparable to those obtained by other procedures with both purified (rat kidney mitochondria) and crude (mouse brain homogenate) preparations. These dye-coupled procedures are potentially applicable to assays of other NADH-producing dehydrogenases in crude preparations.