Reconstitution of the Catalytic Core of F-ATPase (αβ)3γ from Escherichia coli Using Chemically Synthesized Suhunit γ

摘要

ATP synthesis from ADP and P_i accounts for the vast majority of ATP consumed by higher organisms. The ender-gonic reaction requires both, catalysis and the input of free energy, which is provided by the ion motive force across the ATP synthase (F_oF1) containing coupling membrane. Ion flux through the intramembrane portion F_o results in a unidirectional mechanical rotation of the rotor portion of the enzyme. By means of elastic coupling this liberates spontaneously formed, but tightly bound ATP from the reactive sites. In this way the electrochemical potential of the "coupling ion" is mechanically coupled to the chemical reaction. For recent reviews see references [1-4]. ATP synthase works fully reversibly: Upon the expenditure of ion motive force it synthesizes ATP, upon hydrolysis of ATP it generates an ion motive force. These two modes are strictly coupled to clockwise or counterclockwise rotation. It is conceivable that the direction of rotation is linked to the stereochemical configuration of the enzyme.