ATP Synthesis, Chemistry of

The universal carrier of free energy in all living organisms is adenosine triphosphate (ATP). Virtually all energy-requiring biological processes are coupled to the enzymatic hydrolysis of ATP to adenosine diphosphate (ADP) and inorganic phosphate (P[[inf]]i[[/inf]]). The enzyme complex that synthesizes the bulk of the cellular ATP is called F1F0-ATP synthase. F1F0-ATP synthase is found in energy-converting membranes, such as the inner membrane of mitochondria, the plasma membrane of bacteria, and the thylakoid membrane of chloroplasts, where it harnesses the potential energy of a transmembrane electrochemical gradient that is generated during oxidation of foodstuffs or photosynthesis. F1F0-ATP synthase is a rotary molecular motor enzyme: The energy released in the membrane-bound part (F[[inf]]0[[/inf]]) of the enzyme during ion translocation is transmitted to the catalytic sites on the membrane extrinsic part (F[[inf]]1[[/inf]]) via rotation of a central domain made of polypeptides from both F[[inf]]0[[/inf]] and F[[inf]]1[[/inf]]. This specialized topics review summarizes our current understanding of the biological process of ATP synthesis and emphasizes recent insights into the atomic structure of ATP synthase and the fascinating mechanism of subunit-rotation-induced energy coupling.