LANTHANIDE BINDING TO CHLOROPLAST THYLAKOID MEMBRANES

稀土离子独特的光谱和磁学性质 广泛用于探测金属离子与金属离子的相互作用 生物大分子和细胞膜。调查 通常被设计成利用可量化的化学差异 在稀土元素中揭示阳离子在酶中的作用 过程、细胞传输现象和膜结构 决定。这项拟议的研究将试图证明 镧系元素离子大小的变化是一个有效的探针 脂质双分子层的电学性质和生物学特性 膜。该项目将检验这样一种假设，即 三价稀土离子对它们的亲和力和动力学的影响 结合到表面叶绿体类囊体膜上。至 证实这一假说，该原理的特点 三价稀土元素与类囊体膜的相互作用 表面将使用两个荧光探针来确定， 9-氨基吖啶(9-AA)和2-对甲苯基-6-磺酸 (TNS)。当稀土离子被吸附到类囊体上时 膜表面，表面曝光负片的电荷中和 收费就会发生。随后的电荷中和程度 改变9-AA阳离子或TNS阴离子与 膜表面，如荧光变化所证明的 这些离子探针的水平。9AA或TNS的测量 荧光强度与稀土元素浓度的函数关系 将揭示结合位点的同质性，其强度 结合，以及结合位点的竞争。测量 9-AA或TNS荧光强度随时间的变化 使阳离子结合速率的动力学测定成为可能 和移除。稀土元素结合参数的差异， 特别是与镧系元素离子大小有关的 为了进一步描述 类囊体膜与膜电荷机制 中和。这证明了9-AA和 TNS荧光到阳离子尺寸将提供一种新的探针 用于其他生物研究的阳离子-膜平衡 系统。

The unique spectroscopic and magnetic properties of lanthanide ions are widely used to probe the interactions of metal ions with biological macromolecules and cellular membranes. Investigations are often designed to utilize quantifiable chemical differences among the lanthanides to reveal the role of Cations in enzymatic processes, cellular transport phenomena, and membrane Structural determinations. The proposed research will seek to demonstrate that the variation in lanthanide ionic size is an effective probe of the electrical properties of lipid bilayers and biological membranes. The project will test the hypothesis that the sizes of trivalent lanthanide ions influence their affinity and kinetics of binding to the surface chloroplast thylakoid membranes. To substantiate this hypothesis, the principle of features of the interactions of trivalent lanthanides with the thylakoid membrane surface will be determined using two fluorescent probes, 9-aminoacridine (9-AA) and 2-p-toluidinonaphtbalene-6-sulfonate (TNS). As lanthanide cations are adsorbed onto the thylakoid membrane surface, charge neutralization of surface-exposed negative charges occurs. The extent of charge neutralization subsequently alters the proximity of the 9-AA cation or the TNS anion to the membrane surface, as evidenced by variations in the fluorescence levels of theses ionic probes. Measurement of 9AA or TNS fluorescence intensity as a function of lanthanide concentration will reveal the homogeneity of binding sites, the strength of binding, and the competition for binding sites. Measurements of 9-AA or TNS fluorescence intensity as a function of time will enable the kinetic determinations of the rates of cation binding and removal. Differences in the parameters of lanthanide binding, particularly in relation to lanthanide ionic size, will be assessed to further characterize the structural organization of the thylakoid membrane and the mechanism of membrane charge neutralization. This demonstration of the sensitivity of 9-AA and TNS fluorescence to cation size will provide a novel probe of cation-membrane equilibria for the study of other biological systems.