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：2003
卷号：100
期号：3
页码：874-879
DOI：10.1073/pnas.0337432100
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：F1Fo-ATP synthase is the enzyme responsible for most of the ATP synthesis in living systems. The catalytic domain F1 of the F1Fo complex, F1-ATPase, has the ability to hydrolyze ATP. A fundamental problem in the development of a detailed mechanism for this enzyme is that it has not been possible to determine experimentally the relation between the ligand binding affinities measured in solution and the different conformations of the catalytic {beta} subunits ({beta}TP, {beta}DP, {beta}E) observed in the crystal structures of the mitochondrial enzyme, MF1. Using free energy difference simulations for the hydrolysis reaction ATP+H2O [->] ADP+Pi in the {beta}TP and {beta}DP sites and unisite hydrolysis data, we are able to identify {beta}TP as the "tight" (KD = 10-12 M, MF1) binding site for ATP and {beta}DP as the "loose" site. An energy decomposition analysis demonstrates how certain residues, some of which have been shown to be important in catalysis, modulate the free energy of the hydrolysis reaction in the {beta}TP and {beta}DP sites, even though their structures are very similar. Combined with the recently published simulations of the rotation cycle of F1-ATPase, the present results make possible a consistent description of the binding change mechanism of F1-ATPase at an atomic level of detail.
