Turning a biologically important molecular motor at a constant rate saves energy, according to experiments.
Within every biological cell is an enzyme, called adenosine triphosphate (ATP) synthase, that churns out energy-rich molecules for fueling the cell’s activity. New experiments investigate the functioning of this “energy factory” by artificially cranking one of the enzyme’s molecular motors [1]. The results suggest that maintaining a fixed rotation rate minimizes energy waste caused by microscopic fluctuations. Future work could confirm the role of efficiency in the evolutionary design of biological motors.
ATP synthase consists of two rotating molecular motors, Fo and F1, that are oriented along a common rotation axis and locked together so that the rotation of Fo exerts a torque on the shaft in the middle of F1. The resulting motion within F1 helps bring together the chemical ingredients of the molecule ATP, which stores energy that can later be used in cellular processes.