October 3, 2025• Physics 18, 167Turning a biologically important molecular motor at a constant rate saves energy, according to experiments. Energy factory. The enzyme ATP synthase consists of two motors, Fo (orange) and F1 (blue). The enzyme takes in molecular ingredients (shown in red on the left) and assembles them into the molecule ATP, which delivers energy to other parts of the cell (right). Fo is embedded in a membrane (green) and is powered by a flow of protons (blue dots), which genera...