Use of HPLC for the study of ADP binding to chloroplast ATPase. I. Influence of experimental conditions and proposition of mechanism

The binding of ADP to chloroplast ATPase (CF1) has been studied by chromato graphic methods (Hummel and Dreyer method and chromatographic determination of the enzymatic inhibition). The influence of different factors has been studied: temperature, ionic str ength, activation treatments, pyrophosphate fixation. From the comparison o f the dependence of ADP binding land in certain cases, of ATP binding), wit h that of the enzymatic activity, it is shown that the conclusions drawn fo r the dissociation constants cannot be extended to the Michaelis constant. The role of the lysine present in the nucleotide binding sites, already emp hasized by several authors, has been proposed to be the ligand, in the prot onated form, of the negatively charged phosphate groups of ADP or ATP.