de la Peña P, Barros F, Gascón S, Lazo P S, Ramos S
J Biol Chem. 1981 Oct 25;256(20):10420-5.
Killer toxin from Saccharomyces cerevisiae inhibited the pumping of protons into the medium by metabolically active sensitive cells. Such inhibition coincided with that of the uptake of potassium ions which are thought to be accumulated by yeast cells in order to neutralize the membrane potential created because of the extrusion of protons. The consumption of glucose, however, was identical in killer-treated and untreated cells. These alterations can be explained by the ability of the toxin to reduce the chemical proton gradient across the plasma membrane as measured by the accumulation of the weak permeable [14C]propionic acid. With this method, an internal pH of 6.42 was calculated from normal cells (the external pH was 4.6) while that of toxin-treated cells was decreased as a function of time. The proton concentration gradient was reduced from 66- to 17-fold. It is shown that the toxin-induced alteration of the proton gradient is due to an enhanced proton permeability of the yeast plasma membrane upon binding of the toxin. It is suggested that killer toxin acts as a macromolecular proton conductor similar in some respects to the known proton conductors 2,4-dinitrophenol and carbonyl cyanide m-chlorophenylhydrazone, since all the described effects are also observed with these substances.
来自酿酒酵母的杀伤毒素抑制了代谢活跃的敏感细胞将质子泵入培养基的过程。这种抑制作用与钾离子摄取的抑制作用同时发生，钾离子被认为是酵母细胞为了中和由于质子外排而产生的膜电位而积累的。然而，经杀伤毒素处理的细胞和未处理的细胞对葡萄糖的消耗是相同的。这些变化可以通过毒素降低跨质膜的化学质子梯度的能力来解释，这是通过弱渗透性的[14C]丙酸的积累来测量的。用这种方法，正常细胞（外部pH为4.6）的内部pH计算为6.42，而毒素处理细胞的内部pH则随时间降低。质子浓度梯度从66倍降低到17倍。结果表明，毒素诱导的质子梯度变化是由于毒素结合后酵母质膜质子通透性增强所致。有人提出，杀伤毒素作为一种大分子质子导体，在某些方面类似于已知的质子导体2,4-二硝基苯酚和羰基氰化物间氯苯腙，因为用这些物质也观察到了所有上述效应。
