Competition between phosphate and protons on phosphorylation and cation exchange in chloroplasts.

Protons, AsO;, and NH: are competitive inhibitors of Pi in the oxidative esterification of Pi in chloroplasts. Pi, AsO;, NH:, and other monovalent cations are competitive inhibitors of H+ in the cation-H+ exchange reaction of chloroplasts. Since Pi and protons compete for the same electron-activated fixed anionic sites in chloroplasts, it is proposed that the initial energy-requiring step in oxidative phosphorylation is the removal, or activation, of the proton from bound magnesium Pi by the passage of an electron through a semiconducting anionic lattice, possibly acidic lipids, within chloroplasts.