Aug 10, 1981

Inhibition of the mitochondrial nicotinamide nucleotide transhydrogenase by dicyclohexylcarbodiimide and diethylpyrocarbonate

The Journal of Biological Chemistry
D C Phelps, Y Hatefi

Abstract

The mitochondrial nicotinamide nucleotide transhydrogenase enzyme (EC 1.6.1.1) is inhibited by treatment with dicyclohexylcarbodiimide or diethylpyrocarbonate. Both inhibitions are pseudo first order with respect to incubation time, and both reaction orders with respect to inhibitor concentration are close to unit, indicating that in each case inhibition results from the binding of one inhibitor molecule per active unit of the transhydrogenase enzyme. In the presence of either inhibitor, both the energy-linked and the nonenergy-linked transhydrogenation reactions are inhibited at about the same rate. The water-soluble carbodiimide, N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide, showed no inhibition, however, NAD(H) and reduced or oxidized 3-acetylpyridine adenine dinucleotide protected the enzyme against inhibition by dicyclohexylcarbodiimide, while NADP (but not NADPH) appeared to increase the rate of inhibition. Substrates did not protect the enzyme against inhibition by diethylpyrocarbonate. [14C]dicyclohexylcarbodiimide labeled the transhydrogenase enzyme in submitochondrial particles. Treatment of labeled particles with trypsin resulted in fragmentation of the transhydrogenase enzyme and loss of a labeled polypeptide of ...Continue Reading

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Mentioned in this Paper

Abnormal Fragmented Structure
Formic Acids
Pseudo brand of pseudoephedrine
NNT gene
NADH
Trypsin
Soluble
Mitochondria
Carbodiimides
Substrate Specificity

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