The enzyme is found in bacterial plasma membrane, in thylakoid membrane (chloroplast ATP synthase) and in inner mitochondrial membrane. The main function of the enzyme is ATP production.
In this case, the terminal velocity increases to about 320 km/h (200 mph or 90 m/s), which is almost the terminal velocity of the peregrine falcon diving down on its prey.
Roughly 120 mph flat and stable. Head-down is much faster, but is not stable (it takes active control). Terminal velocity is when the gravity force upon an object is equal to that of the wind resistance.