Human muscle pyruvate dehydrogenase activity.

Muscle pyruvate dehydrogenase complex (PDHC) activity was studied in 70 patients with different neuromuscular disorders. Children had higher total PDHC and lipoamide dehydrogenase (LAD) activities than adults. There were no significant differences in muscle PDHC activity in patients with Friedreich ataxia, patients with other ataxias, or age-matched controls. Kinetic analysis of LAD showed no differences in Km for lipoamide between Friedreich ataxia patients and controls.