Electrochemical proton gradient across the cell membrane of Halobacterium halobium: effect of N,N'-dicyclohexylcarbodiimide, relation to intracellular adenosine triphosphate, adenosine diphosphate, and phosphate concentration, and influence of the potassium gradient.

摘要: The proton motive force across the cell membrane of halobacterial cells has been estimated and compared to intracellular values ATP, ADP, inorganic phosphate concentrations with respect chemiosmotic hypothesis. accumulation 14C-labeled indicator substances, triphenylmethylphosphonium for potential 5,5-dimethyloxazolidine-2,4-dione pH difference between interior medium, measured in cells. Values up 270 mV have found pretreated N,N'-dicyclohexylcarbodiimide (DCCD, 10(-4) M, 30 degrees C, 12 h). Upon illumination a high is generated, which then gradually replaced by large difference. Cells treated lower DCCD show only an enhancement upon illumination; remains at low level. Under anaerobic dark conditions, untreated maintain 120-140 mV, equilibrated levels phosphate. gradient 1 unit 6 but 0 8. (60-80 mV) (120-130 We propose that translocating ATPase compensates lowered external enhancing potential. concentration potassium ions influences ATP levels, apparently via its action on When chemical ion, expressed millivolts, exceeds preexisting potential, level enhanced. ion (millivolts) smaller than decreased.