Tan Ming-Liang, Balabin Ilya, Onuchic José Nelson
Center for Theoretical Biological Physics and Department of Physics, University of California at San Diego, La Jolla, California 92093-0374, USA.
Biophys J. 2004 Mar;86(3):1813-9. doi: 10.1016/S0006-3495(04)74248-4.
Cytochrome c oxidase mediates the final step of electron transfer reactions in the respiratory chain, catalyzing the transfer between cytochrome c and the molecular oxygen and concomitantly pumping protons across the inner mitochondrial membrane. We investigate the electron transfer reactions in cytochrome c oxidase, particularly the control of the effective electronic coupling by the nuclear thermal motion. The effective coupling is calculated using the Green's function technique with an extended Huckel level electronic Hamiltonian, combined with all-atom molecular dynamics of the protein in a native (membrane and solvent) environment. The effective coupling between Cu(A) and heme a is found to be dominated by the pathway that starts from His(B204). The coupling between heme a and heme a(3) is dominated by a through-space jump between the two heme rings rather than by covalent pathways. In the both steps, the effective electronic coupling is robust to the thermal nuclear vibrations, thereby providing fast and efficient electron transfer.
细胞色素c氧化酶介导呼吸链中电子传递反应的最后一步，催化细胞色素c与分子氧之间的电子传递，并同时将质子泵过线粒体内膜。我们研究细胞色素c氧化酶中的电子传递反应，特别是核热运动对有效电子耦合的控制。使用格林函数技术和扩展休克尔能级电子哈密顿量计算有效耦合，并结合蛋白质在天然（膜和溶剂）环境中的全原子分子动力学。发现Cu(A)与血红素a之间的有效耦合主要由始于His(B204)的路径主导。血红素a与血红素a(3)之间的耦合主要由两个血红素环之间的空间跳跃而非共价路径主导。在这两个步骤中，有效电子耦合对热核振动具有鲁棒性，从而实现快速高效的电子传递。
