The Proton Electrochemical Gradient in Escherichia coli Cells

摘要: The internal pH of Escherichia coli cells was estimated from the distribution either 5,5-[14C]dimethyl-2,4-oxazolidinedione or [14C]methylamine. EDTA/valinomycin treatment employed to estimate delta psi 86Rb+ concomitant with for calculation muH. Respiring intact maintained an more alkaline by 0.63-0.75 unit than that milieu at extracellular 7, both in growth medium and KCl solutions. decreased when respiration inhibited anaerobiosis presence KCN. muH, established EDTA/valinomycin-treated cells, constant (122-129 mV) over potassium concentration 0.01 mM-1 mM. At lower (110-120 predominant component, higher increased 0.7 units (42 mV). 150 mM muH reduced 70 mV mostly due a component 0.89 (53 interchangeability components is consistent electronic proton pump serving as counter ion valinomycin. Indeed parameters carbonylcyanide p-trifluoromethoxyphenylhydrazone. highest 2 observed 6; increasing 0 7.65 -0.51 9. A similar pattern dependence on but almost whole range values (6-8) implying electroneutral movement. Potassium specifically required EDTA-treated E. K12 since other monovalent divalent cations could not replace valinomycin required.