Simpson S J, Bendall M R, Egan A F, Vink R, Rogers P J
Eur J Biochem. 1983 Oct 17;136(1):63-9. doi: 10.1111/j.1432-1033.1983.tb07705.x.
High-field 31P-NMR studies of whole cells of Streptococcus faecalis have shown that delta pH can be formed by ATP hydrolysis and also by lactate transport. We have used 31P-NMR to measure the pH dependence of the variable stoichiometry of the proton/lactate carrier. At low external pH (pH approximately equal to 6.5) the influx stoichiometry was 1.1 H+/lactate, while at high pH (7.5) the ratio was almost 2; the apparent midpoint pH of this variable stoichiometry is 7. delta psi measurements support the electrogenic nature of lactate transport at high pH; the variable rate of membrane depolarization caused by lactate transport also had a midpoint near pH 7.0. The data is consistent with a symmetrical carrier operating with variable stoichiometry as proposed by Michels et al.
粪肠球菌全细胞的高场31P - NMR研究表明，ΔpH可通过ATP水解形成，也可通过乳酸转运形成。我们已使用31P - NMR来测量质子/乳酸载体可变化学计量比的pH依赖性。在低外部pH（pH约等于6.5）时，流入化学计量比为1.1 H⁺/乳酸，而在高pH（7.5）时，该比例几乎为2；这种可变化学计量比的表观中点pH为7。Δψ测量结果支持高pH时乳酸转运的生电性；由乳酸转运引起的膜去极化变化速率在pH 7.0附近也有一个中点。这些数据与Michels等人提出的以可变化学计量比运行的对称载体一致。
