Kotyk A, Dvoraková M, Georghiou G
Department of Membrane Transport, Czech Academy of Sciences, Prague.
Biochem Int. 1992 Dec;28(6):1089-96.
Saccharomyces cerevisiae, Schizosaccharomyces pombe, Endomyces magnussi, Lodderomyces elongisporus and Rhodotorula gracilis, yeast species ranging from a glycolytic type to a strictly aerobic one, were tested for the activity of their plasma membrane H(+)-ATPase and the effect of alkaline metal cations thereon. The ATP-hydrolyzing activity of membranes from glucose-activated cells ranged from 456 to 932 mumol inorganic phosphate released per min per 1 g membrane protein. The effect of 0.2 M Li+, Na+, K+, Rb+ and Cs+ never exceeded the statistical range of error. In contrast, acidification after glucose addition ranged from 0.15 (for R. gracilis) to 14.8 nmol H+ per min per mg dry weight (for S. cerevisiae) and it was markedly influenced by the presence of alkaline metal chlorides, the highest effect observed being a seven-fold increase by K+ in a S. cerevisiae suspension. The effects were additive to those observed without ions in solution and are ascribed to the operation of independent channels and/or exchange systems for H+ with a clear selectivity toward K+. The separate nature of the ion-triggered extracellular acidification is supported by a different ratio of titration to pH-derived acidity with and without K+.
对酿酒酵母、粟酒裂殖酵母、马格努斯内孢霉、长孢洛德酵母和纤细红酵母等从糖酵解型到严格需氧型的酵母菌种，测试了其质膜H(+)-ATP酶的活性以及碱金属阳离子对其的影响。葡萄糖激活细胞的膜的ATP水解活性为每分钟每1克膜蛋白释放456至932微摩尔无机磷酸盐。0.2M的Li+、Na+、K+、Rb+和Cs+的影响从未超过统计误差范围。相比之下，添加葡萄糖后的酸化程度为每分钟每毫克干重0.15（对于纤细红酵母）至14.8纳摩尔H+（对于酿酒酵母），并且它受到碱金属氯化物存在的显著影响，观察到的最大影响是酿酒酵母悬浮液中K+使其增加了七倍。这些影响与在溶液中无离子时观察到的影响相加，并且归因于独立的H+通道和/或交换系统的运作，对K+具有明显的选择性。离子触发的细胞外酸化的独立性质得到了有K+和无K+时滴定与pH衍生酸度的不同比率的支持。
