Mg^(2+)离子对紫膜表面电位效应的自旋探针—ESR研究  

SPIN LABEL-ESR STUDIES OF THE EFFECT OF Mg^+ ON SURFACE POTENTIAL OF PURPLE MEMBRANE

作　　者：张衡涛 张克[1] 孙纹琦 谈曼琪 

机构地区：[1]中国科学院生物物理所

出　　处：《生物物理学报》1989年第3期281-286,共6页Acta Biophysica Sinica

基　　金：国家自然科学基金资助

摘　　要：本文根据带正电荷自旋探针CAT_(12)在紫膜结合相和水相的分布,利用自旋探针顺磁共振(ESR)技术测定了Mg^(2+)对紫膜表面电位的影响,我们的结果表明紫膜具有σ为3.02×10^(-4)Ch-arges/(?)~2的表面电荷密度.据此σ用Gouy-Chapman理论计算得到Mg^(2+)离子浓度与表面电位((?)_i)的关系与实验结果极为一致,这表明离子通过表面电位的变化引起紫膜的表面pH值的改变从而影响紫膜的结构与功能,Mg^(2+)对紫膜表面电位的影响明显地比K^+要大,说明镁离子可能在紫膜的结构与功能中有更为重要的作用.The effect of mg2+ on surface potential changes of purple membrane wasdetermined by detecting the distribution of the positively charged, paramagnetic amphiphile probe CAT12 (4-(dodecylmethylammonium) -l-oxyl-2, 2, 6, 6-tetra-methylpiperdine iodine) in aqueous-free and membrane-bound phases. The result showed that surface charge densities σ of purple membrane was 3.02×10-4 charges/A2. The relation between concentration of Mg2+ and surface potential (Ψi) which is calculated from Gouy-Chapman theory is identical with that from experiment. The suggests the ions change the surface-pH with surface potential and then affect the stucture and function of purple membrane. The effect of Mg2+ on surface potentials of purple membrabe is greater than that of K+ . It means that Mg2+ probably plays a more important role in the structure and function of purple membrane.

关 键 词：表面电位 自旋探针 ESR 紫膜 镁 

分 类 号：Q6－33[生物学—生物物理学]