Net proton uptake is preceded by multiple proton transfer steps upon electron injection into cytochrome c oxidase.

ABSTRACT: Cytochrome c oxidase (COX), the last enzyme of the respiratory chain of aerobic organisms, catalyzes the reduction of molecular oxygen to water. It is a redox-linked proton pump, whose mechanism of proton pumping has been controversially discussed, and the coupling of proton and electron transfer is still not understood. Here, we investigated the kinetics of proton transfer reactions following the injection of a single electron into the fully oxidized enzyme and its transfer to the hemes using time-resolved absorption spectroscopy and pH indicator dyes. By comparison of proton uptake and release kinetics observed for solubilized COX and COX-containing liposomes, we conclude that the 1-μs electron injection into Cu(A), close to the positive membrane side (P-side) of the enzyme, already resu

SUBMITTER: Kirchberg K 

PROVIDER: S-EPMC3318725 | biostudies-literature | 2012 Mar

REPOSITORIES: biostudies-literature