Inhibition by quinaldate of dehydrogenases

Quinaldate (quinoline-2-carboxylate) inhibits pyridine-, and flavin nucleotide-dependent dehydrogenases, both inside the mitochondria and in isolated form. Other mitochondrial functions and some other isolated enzymes (with one exception) are not influenced by quinaldate at all. Thus, quinaldate can be regarded as a specific "dehydrogenase inhibitor". The inhibition of alcohol dehydrogenase (EC 1.1.1.1) and lactate dehydrogenase (EC 1.1.1.27) by quinaldate is of mixed type, both with respect to NAD+ and ethanol or lactate, respectively. The Ki for alcohol dehydrogenase is 4.5 mM, that of lactate dehydrogenase 7.5 mM. It can be assumed that the inhibition by quinaldate of dehydrogenases is a consequence of its binding to that part of the active centre which takes part in the dehydrogenation itself and might possess very similar structure in all dehydrogenases.