Solvent Isotope Effect on the Reaction Catalysed by the Pyruvate Dehydrogenase Complex from Escherichia coli

Author:

Liu X.,Bisswanger H.

Abstract

AbstractThe pyruvate dehydrogenase from Escherichia coli showed a primary kinetic isotope effect when its overall reaction or the partial reaction of the pyruvate dehydrogenase component were tested in deuterium oxide. The Michaelis constants for pyruvate were nearly unchanged, but the maximum velocities in water and deuterium oxide differed, their ratio being DV = 1.7 for the overall reaction and DV = 2.1 for the E1p reaction. The pH profile and, accordingly, the δpK1 and δpK2 values were shifted by 0.6 units to higher pL values. A linear proton inventory curve was obtained when varying the atom fractions of protons relative to deuterons from 100 to 0%. This is an indication for a single proton transfer. It is proposed that this relatively weak primary isotope effect may be caused by the protonation of the N1 nitrogen at the pyrimidine ring of the cofactor by an adjacent glutamate residue. The proton of its carboxylic group exchanges very fast with deuterons of the solvent.

Publisher

Walter de Gruyter GmbH

Subject

Clinical Biochemistry,Molecular Biology,Biochemistry

Cited by 2 articles. 订阅此论文施引文献 订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献

1. Biochemical Effects of Deuterium Oxide and Deuteration;Deuterium Oxide and Deuteration in Biosciences;2022

2. Metabolic adaptability in hexavalent chromium-treated renal tissue: an in vivo study;Clinical Kidney Journal;2017-07-27

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