Protons, proteins and ATP.

The machinery of life has been disclosed in the second half of the 20th century to a degree not in the least envisioned previously by even the most daring players in this field. It has been extremely rewarding to start out from the fogs and to enjoy the brightness at the end of one's active career. Perhaps the most astounding lesson to learn is how conservative and modular is the construction of key devices. Oxidative and photophosphorylation are carried out by ATP synthase, which is unique in converting electrochemical, mechanical and chemical forms of energy within one nano-machine. This complex protein consists of more than 20 polypeptides of at least eight different kinds. Still, its activity survives in engineered chimerical constructs joining parts from organisms that underwent billions of years of separate evolution. The path of discovery of its structure and function is sketched here from a personal viewpoint. It has been a long way from before-structure-bioenergetics to the post-structural one (which now dominates the biology textbooks), but there is still a long way to go for a rigorous physical understanding. The author has been privileged to enjoy the friendship, cooperation and competition of excellent scientists from widely different backgrounds and expertise.