THE H+ ATP COUPLING RATIO OF THE ATP SYNTHASE FROM THIOL-MODULATED CHLOROPLASTS AND 2 CYANOBACTERIAL STRAINS IS 4/

In this paper the authors emphasise that the proton translocating ATP synthase from thiol-modulated chloroplasts and two cyanobacterial stra ins has a coupling ratio of 4 protons per ATP synthesised or hydrolyse d, This ratio is determined by several thermodynamic studies at equili brium between phosphate potential (Delta G(p)) and proton gradient (<D elta(mu)over bar> (H+)>), and is confirmed by measurement of proton fl ux during ATP hydrolysis, Ratios lower than 4 H+/ATP that have been pu blished in the past have predominantly been determined with the oxidis ed chloroplast enzyme. Errors in these measurements will be discussed.