Oxidative decarboxylation of pyruvate to form acetyl–coenzyme A, a crucial step in many metabolic pathways, is carried out in most aerobic organisms by the multienzyme complex pyruvate dehydrogenase.

Enzymes that use the cofactor thiamin diphosphate (ThDP, 1), the biologically active form of vitamin B 1, are involved in numerous metabolic pathways in all organisms. Although a theory of the ...