Fig. 8. Investigation of H+ counter-transport and development of transmembrane potential in CmΔZntA proteoliposomes. (a) Determination of H+ counter-ion transport via monitoring luminal pH changes as a function of time with the pH-indicator pyranine (1 mM) under conditions utilized in metal substrate transport assays (M2+ = 40 μM). Measurements were corrected for background signals of control liposomes. All data are mean ± s.d. (n = 3). (b) Real-time measurements of transmembrane potential generation in CmΔZntA proteoliposomes under conditions utilized for metal transport (M2+ = 40 μM), determined upon encapsulating the membrane potential probe Oxonol VI in the proteoliposome lumen as described in Materials and methods. Control experiment in the absence of Mg2+ are reported and labeled (no Mg2+). Signals were corrected for background values for control liposomes. Data are mean ± s.d. (n = 3).
