Regulation of the Ascaris suum pyruvate dehydrogenase complex by phosphorylation and dephosphorylation

The pyruvate dehydrogenase complex isolated from 'anaerobic' mitochondria of Ascaris suum has a subunit composition similar to complexes isolated from most other eukaryotic organisms and is regulated by phosphorylation and dephosphorylation. Pyruvate dehydrogenase kinase activity is stimulated by NADH and a number of physiologically important acyl-CoA intermediates and is inhibited by CoA, propionate, tiglate and pyruvate. It is suggested that the elevated levels of pyruvate observed in the ascarid organelle may be important in maintaining the pyruvate dehydrogenase complex in an active state, even in the presence of a reduced pyridine nucleotide pool.