期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2005
卷号：102
期号：19
页码：6795-6800
DOI：10.1073/pnas.0408117102
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Proton translocation in the D-pathway of cytochrome c oxidase has been studied by a combination of classical molecular dynamics and the multistate empirical valence bond methodology. This approach allows for explicit Grotthuss proton hopping between water molecules. According to mutagenesis experiments, the role of proton donor/acceptor along the D-pathway is carried by the highly conserved residue Glu-242. The present multistate empirical valence bond simulations indicate that the protonation/deprotonation state of Glu-242 is strongly coupled to the distance of proton propagation in the D-pathway. The proton was seen to travel the full length of the D-pathway when Glu-242 was deprotonated; however, it was trapped halfway along the path when Glu-242 was protonated. Further investigation in terms of both proton dynamical properties and free energy calculations for the pathway of proton transport provides evidence for a two-step proton transport mechanism in the D-pathway.
