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. Author manuscript; available in PMC: 2010 Oct 6.
Published in final edited form as: Biochemistry. 2009 Oct 6;48(39):9250–9255. doi: 10.1021/bi9014067

Fig. 5.

Fig. 5

Effect Δμ̃H+ (interior negative and alkaline) on the lactose efflux. RSO membrane vesicles in 100 mM KPi (pH 7.5) were pre-equilibrated with 10 mM [14C]lactose (10 mCi/mmol) in the presence of 55 μM valinomycin and diluted 200-fold into 100 mM KPi at pH 7.5 [wild type LacY (λ, n = 1) or D240E mutant (σ, n = 2)] or 100 mM NaPi at pH 5.5 [wild type LacY (μ, n = 1) or D240E mutant (Δ, n = 3)]. Reactions were terminated by quenching and rapid filtration at given times. The average percentage of lactose retained is plotted as a function of time.