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Function of the F 1 ‐motor (F 1 ‐ATPase) of ATP synthase by apolar—polar repulsion through internal interfacial water
Author(s) -
Urry Dan W.
Publication year - 2006
Publication title -
cell biology international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.932
H-Index - 77
eISSN - 1095-8355
pISSN - 1065-6995
DOI - 10.1016/j.cellbi.2005.09.011
Subject(s) - chemistry , hydrophobic effect , atp synthase , aqueous solution , phosphate , atpase , polar , chemiosmosis , gibbs free energy , electrostatics , proton , crystallography , chemical physics , organic chemistry , thermodynamics , enzyme , physics , astronomy , quantum mechanics
Thesis : Within the structurally‐confined internal aqueous cavity of the F 1 ‐motor of ATP synthase, function results from free energy changes that shift the balance between interfacial charge hydration and interfacial hydrophobic hydration. Transition state description : At the β‐P end of ADP · Mg occurs an inorganic phosphate, P i . This P i resides at the base of a water‐filled cleft that functions like an aperture to focus, into an aqueous chamber, a competition for hydration (an apolar—polar repulsion) between charged phosphate and hydrophobic surface of the γ‐rotor. Two means available for the phosphate and the hydrophobic surface to improve their hydration free energies are physically to separate by rotation of the γ‐rotor or chemically to combine P i with ADP to form less charged ATP. This proposal derives from calculated changes in Gibbs free energy for hydrophobic association of amino acid side chains and chemical modifications thereof and from experimentally demonstrated water‐mediated repulsion between hydrophobic and charged sites that resulted from extensive studies on designed elastic‐contractile model proteins.