Electrocatalytic evidence of the diversity of the oxygen reaction in the bacterial bd oxidase from different organisms.

Cytochrome bd oxidase is a bacterial terminal oxygen reductase that was suggested to enable adaptation to different environments and to confer resistance to stress conditions. An electrocatalytic study of the cyt bd oxidases from Escherichia coli, Corynebacterium glutamicum and Geobacillus thermodenitrificans gives evidence for a different reactivity towards oxygen. An inversion of the redox potential values of the three hemes is found when comparing the enzymes from different bacteria. This inversion can be correlated with different protonated glutamic acids as evidenced by reaction induced FTIR spectroscopy. The influence of the microenvironment of the hemes on the reactivity towards oxygen is discussed.