Metalloenzymes as molecular switches: the role of conformation changes in controlling activity

Enzymatically important conformation changes have been classified according to the nature of the trigger (capital S, I, A for substrate, reaction intermediate, allosteric modifier) and the rate of change (subscript f or s, if fast or slow relative to the enzymatic reaction). It is suggested that, in Cu superoxide dismutase, the known protonation of the product (to give H2O2) under nonequilibrium conditions involves an essentially irreversible If change.