Open AccessPyruvate Dehydrogenase, Substrate Specificity and Product Inhibition
Author(s) -
Bremmer J.
Publication year - 1969
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1969.tb00559.x
Subject(s) - pyruvate decarboxylation , pyruvate dehydrogenase complex , pyruvate dehydrogenase phosphatase , pyruvate dehydrogenase kinase , nad+ kinase , dihydrolipoyl transacetylase , biochemistry , enzyme , oxoglutarate dehydrogenase complex , glycerol 3 phosphate dehydrogenase , dehydrogenase , chemistry , substrate (aquarium) , branched chain alpha keto acid dehydrogenase complex , pyruvate carboxylase , product inhibition , non competitive inhibition , biology , ecology
1 Studies with intact mitochondria and with soluble pyruvate dehydrogenase indicate that pyruvate and α‐ketobutyrate are oxidized by the same enzyme (pyruvate dehydrogenase), while α‐ketovalerate is oxidized by a different enzyme. 2 Pyruvate and α‐ketobutyrate have about the same affinity for the enzyme, but pyruvate is oxidized at a much higher rate. 3 Acetyl‐CoA and propionyl‐CoA both behave as competitive inhibitors to CoA. The K i for both is slightly higher than the K m for CoA. Accordingly the enzyme is only moderately inhibited by a high acetyl‐CoA/CoA ratio. 4 NADH behaves mainly as a competitive inhibitor to NAD. The K i is significantly lower than the K m for NAD. Accordingly the enzyme is strongly inhibited by a high NADH/NAD ratio. 5 The significance of these properties of the enzyme for the regulation of the activity of pyruvate dehydrogenase in vivo is discussed.