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.
Terminal velocity is the speed where drag equals thrust. Drag is proportional to speed while thrust typically isn't, so as you go faster, drag increases until it cancels out all the thrust and you can't go any faster. Drag is also proportional to atmospheric density, so terminal velocity varies with altitude.