Kinetic coupling between electron and proton transfer in cytochrome c oxidase: Simultaneous measurements of conductance and absorbance changes

摘要

Bovine heart cytochrome c oxidase is an elec- tron-current driven proton pump. To investigate the mechanism by which this pump operates it is important to study individual electron- and proton-transfer reactions in the enzyme, and key reactions in which they are kinetically and thermodynamically coupled. In this work, we have simultaneously measured absor- bance changes associated with electron-transfer reactions and conductance changes associated with protonation reactions fol- lowing pulsed illumination of the photolabile complex of partly reduced bovine cytochromec oxidase and carbon monoxide.