EMAIL THIS PAGE TO A FRIEND

Journal of bioenergetics and biomembranes

Effect of pH on the steady state kinetics of bovine heart NADH: coenzyme Q oxidoreductase.


PMID 14740890

Abstract

Complete initial steady state kinetics of NADH-decylubiquinone (DQ) oxidoreductase reaction between pH 6.5 and 9.0 show an ordered sequential mechanism in which the order of substrate bindings and product releases is NADH-DQ-DQH2-NAD+. NADH binding to the free enzyme is accelerated by protonation of an amino acid (possibly a histidine) residue. The NADH release is negligibly slow under the turnover conditions. The rate of DQ binding to the NADH-bound enzyme and the maximal rate at the saturating concentrations of the two substrates, which is determined by the rates of DQH2 formation in the active site and releases of DQH2 and NAD+ from the enzyme, are insensitive to pH, in contrast to clear pH dependencies of the maximal rates of cytochrome c oxidase and cytochrome bc1 complex. Physiological significances of these results are discussed.

Related Materials

Product #

Image

Description

Molecular Formula

Add to Cart

D7911
Decylubiquinone, ≥97% (HPLC)
C19H30O4