从溶壁微球菌分离出的膜的阳离子结合能力。
Cation-binding capacity of membranes isolated from Micrococcus lysodeikticus.
作者信息
Cutinelli C, Galdiero F, Tufano M A
出版信息
J Bacteriol. 1969 Oct;100(1):123-7. doi: 10.1128/jb.100.1.123-127.1969.
A study was made of H(+), Na(+), K(+), Ca(++), and Mg(++) binding and ion-exchange properties of the plasma-mesosome membrane system isolated from Micrococcus lysodeikticus strain NCTC 2665. Titration curves were obtained on membranes prepared according to the method of M. R. J. Salton and further exposed to pH 4 for 4 hr (membranes-H). The dissociation coefficients and binding capacities were obtained by applying the mass law equation and the plot of G. Schatchard to the data. The membranes-H possess four kinds of dissociable groups with pK 4.96, 4.18, 3.60, and 3.09, respectively, and a total binding capacity of 0.65 meq/g (dry weight). Potentiometric titrations of cations in the presence and in the absence of membranes-H show that cations (Na(+), K(+), Ca(++), and Mg(++)) are bound by the dissociated groups of the membrane. The fall in pH value for bivalent cations is greater than that for monovalent cations. Cations of the same valency produce equal diminutions on pH. Furthermore, ion-exchange tests carried out on membranes saturated with Mg(++) or Na(+) and suspended in a medium containing (45)Ca show that the cations are reversibly bound.
对从溶壁微球菌菌株NCTC 2665中分离出的质膜-间体膜系统的H⁺、Na⁺、K⁺、Ca²⁺和Mg²⁺结合及离子交换特性进行了研究。按照M. R. J. 索尔顿的方法制备膜，并将其进一步暴露于pH 4的环境中4小时（膜-H），得到了滴定曲线。通过将质量定律方程和G. 斯卡查德图应用于数据，获得了解离系数和结合容量。膜-H具有四种可解离基团，其pK分别为4.96、4.18、3.60和3.09，总结合容量为0.65 meq/g（干重）。在有和没有膜-H存在的情况下对阳离子进行电位滴定表明，阳离子（Na⁺、K⁺、Ca²⁺和Mg²⁺）被膜的解离基团结合。二价阳离子导致的pH值下降大于一价阳离子。相同价态的阳离子对pH的降低作用相同。此外，对用Mg²⁺或Na⁺饱和并悬浮在含有⁴⁵Ca的介质中的膜进行离子交换测试表明，阳离子是可逆结合的。
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