|
|
Rotation of the Fo-ATPase. Fo-ATPase as a proton-driven, rotary stepping motor, as proposed by Junge (1997). The inner ring, with twelve proton or hydrogen atom binding sites, is coupled mechanically to F1-g. The sense of rotation of the inner ring of Fo, viewed from the top, is anticlockwise during ATP synthesis (as shown), when protons move inwards, down the gradient of electrochemical potential. If Fo remains coupled to F1-g during ATP hydrolysis, outward proton translocation will be driven by clockwise rotation of the inner ring. The animation shows one complete rotation of Fo for each pulse of proton motive force. One rotation is driven by inward translocation of twelve protons, and drives synthesis of three ATP molecules by means of mechanical coupling to F1 - one ATP for each 120 ° turn. One rotation of the chloroplast (C)F1 has been timed at 100 ms - pts = 1.
|