The stochastic modeling of proton pumping in cytochrome c oxidase: the contribution of the K-channel

The influence of pH on the activity of cytochrome c oxidase is investigated using the stochastic modelling based on Markov processes. The functioning of the K-channel is considered on four different schemes. A change of channel modes can be observed under high values of pH: the fraction of K-protons transferred through the membrane increases significantly while D-proton flow disappears. Moreover, the pumping efficiency at high pH values rises more than twice under the circumstances when at the beginning of the pumping there are three or four protons in the binuclear center under pumping both D- and K-protons. (paper)