Respiration-driven proton translocation in Escherichia coli

Measurements were made of the stoicheiometry of respiration-driven proton translocation coupled to the oxidation of NAD(P)-linked or flavin-linked substrates in intact cells of Escherichia coli. Observed stoicheiometries (-->H(+)/O quotient; Mitchell, 1966) were approx. 4 with l-malate as substrate and approx. 2 for succinate, d-lactate and glycerol oxidation. It is concluded that the potential number of equivalent energy-conservation sites associated with the respiratory chain is 2 in aerobically grown cells of E. coli harvested during the exponential phase of growth.