title: Thermodynamic efficiency and mechanochemical coupling of F1-ATPase.
abstract: F(1)-ATPase is a nanosized biological energy transducer working as part of F(o)F(1)-ATP synthase. Its rotary machinery transduces energy between chemical free energy and mechanical work and plays a central role in the cellular energy transduction by synthesizing most ATP in virtually all organisms. However, information about its energetics is limited compared to that of the reaction scheme. Actually, fundamental questions such as how efficiently F(1)-ATPase transduces free energy remain unanswered. Here, we demonstrated reversible rotations of isolated F(1)-ATPase in discrete 120° steps by precisely controlling both the external torque and the chemical potential of ATP hydrolysis as a model system of F(o)F(1)-ATP synthase. We found that the maximum work performed by F(1)-ATPase per 120° step is nearly equal to the thermodynamical maximum work that can be extracted from a single ATP hydrolysis under a broad range of conditions. Our results suggested a 100% free-energy transduction efficiency and a tight mechanochemical coupling of F(1)-ATPase.
authors: Department of Physics, Faculty of Science and Engineering, Chuo University, Tokyo 112-8551, Japan.
authors: Shoichi
authors: S
authors: Toyabe
authors: Takahiro
authors: T
authors: Watanabe-Nakayama
authors: Tetsuaki
authors: T
authors: Okamoto
authors: Seishi
authors: S
authors: Kudo
authors: Eiro
authors: E
authors: Muneyuki
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D006868:Hydrolysis; D006180:Proton-Translocating ATPases / Q000378:metabolism*; D013816:Thermodynamics
chemical_list: D000255:Adenosine Triphosphate; D006180:Proton-Translocating ATPases