FoF1-ATP synthases catalyze the formation of ATP from ADP and inorganic phosphate in the
membranes of mitochondria, chloroplasts and bacteria. Endergonic ATP synthesis is coupled to proton translocation across the membrane and is driven by a difference of the electrochemical potential of protons, which is generated by oxidative phosphorylation or by photosynthesis. FoF1-ATP synthase contains two rotary motors converting electrochemical energy via a mechanical form of energy to chemical energy.
We apply a single-molecule spectroscopy approach to monitor the internal rotation of the g-subunit of the F1 portion against its static counterparts, the a- or b-subunits of the Fo portion. In addition, we investigate the rotation and conformational changes of the e-subunit of the F1 portion which might regulate the direction of catalysis, i.e. control of ATP synthesis or ATP hydrolysis. Currently the Fo motor step size (c-subunit movement versus the a-subunit) and elastic energy storage in the central stalk connecting the two motors are analyzed. | 
