How fast is ATP synthase?
For simplicity let us leave aside the more “biochemical”, but less understandable values of “micromoles of ATP per minute per mg protein” and discuss the number of ATP molecules synthesized (or hydrolyzed) by one ATP synthase in one second. Maximal rates over 100 s-1 were reported for bacterial, mitochondrial and chloroplast enzymes for ATP synthesis. ATP hydrolysis rates is a less clear issue, for the coupled enzyme in small membrane vesicles (most commonly used experimental system) quickly builds up relatively high protonmotive force that acts as a back pressure and stops the hydrolysis. For uncoupled or solubilized enzyme rates over 100 s-1 were also reported. In the living cell the enzyme most probably operates below the maximal possible rate, making tens of ATP molecules per second.
