Flow-flash kinetics of O2 binding to cytochrome c oxidase at elevated [O2]: observations using high pressure stopped flow for gaseous reactants

Biochemical and Biophysical Research Communications
J A BaileyW H Woodruff

Abstract

A high-pressure stopped-flow apparatus developed in our laboratories provides the capability to use dissolved gaseous reactants at elevated concentrations in solution (in equilibrium with gas pressures up to ca. 30 atm) for measurement of reaction kinetics. We have used this apparatus to follow the reaction of dioxygen with bovine cytochrome c oxidase following photolysis of the fully reduced CO ligated enzyme up to a dioxygen concentration of 16 mM. The observed rate dependence on [02] follows saturation kinetics and was fit to a limiting rate of 1.0 X 10(6) s(-1). This value is approximately the same as that for the thermal loss of CO to solution from the transient CuB bound state formed upon photolysis of the heme-CO complex. Implications for the mechanism of O2 binding and reduction by the heme-copper oxidases are discussed.

Citations

Nov 10, 2004·Proceedings of the National Academy of Sciences of the United States of America·Eric PiletMarten H Vos
Jul 1, 1998·Annual Review of Biophysics and Biomolecular Structure·H MichelA Kannt
Apr 22, 2004·Biochimica Et Biophysica Acta·Olöf Einarsdóttir, Istvan Szundi
Mar 4, 2006·Journal of Inorganic Biochemistry·J Martin Bollinger, Carsten Krebs
Dec 25, 2019·Biophysical Journal·Istvan SzundiÓlőf Einarsdóttir
Dec 30, 2006·Analytical Chemistry·Michael W ToepkeR Brian Dyer

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