ATP synthesis and hydrolysis in chloroplast membranes. Differential inhibition by antibodies to chloroplast coupling factor 1.
1. Divalent antibodies against chloroplast coupling factor 1 inhibited the factor ATPase, ATP synthesis, hydrolysis and Pi-ATP exchange in chloroplasts. These antibodies also inhibited coupled electron flow rates but not the basal or uncoupled rates. 2. Several types of non-precipitating, modified antibodies prepared from the original antibody preparation strongly inhibited the ATPase and Pi-ATP exchange reaction but had little effect on ATP formation. 3. It is suggested that the inhibition of ATP synthesis by the divalent antibodies is probably due to an indirect blocking of the active site, while the inhibition of ATP-utilizing reactions by the modified antibodies is related to their effect on the transfer of ATP from a non-catalytic to a catalytic site on coupling factor 1, via an energy-dependent conformational change.
D000255:Adenosine Triphosphate / Q000096:biosynthesis* / Q000378:metabolism; D000937:Antigen-Antibody Reactions; D002736:Chloroplasts / Q000378:metabolism*; D006868:Hydrolysis; D007140:Immunoglobulin Fab Fragments; D007425:Intracellular Membranes / Q000378:metabolism; D010785:Photophosphorylation; D010944:Plants; D006180:Proton-Translocating ATPases / Q000276:immunology / Q000378:metabolism*
D007140:Immunoglobulin Fab Fragments; D000255:Adenosine Triphosphate; D006180:Proton-Translocating ATPases