CHARGE TRANSFER ACROSS INTERFACES OF BIOLOGICAL SYSTEMS

生物系统界面间的电荷转移

• 批准号: 2174516
• 负责人: DAVID C MAUZERALL
• 金额: $ 18.49万
• 依托单位: ROCKEFELLER UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1978
• 资助国家: 美国
• 起止时间: 1978-07-01 至 1996-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2174516
• 关键词: bacteriorhodopsins; chemical kinetics; electrochemistry; electron transport; ion transport; ionic bond; lipid bilayer membrane; membrane channels; membrane model; membrane permeability; membrane potentials; oxidation reduction reaction; photochemistry; thermodynamics

The aim of this research is to increase our understanding of charge transfer across biological interfaces, a process vital to all living cells. The planar lipid bilayer is used as the model of cellular inter- faces. The transfer of charge across the lipid bilayer-water interface and across the bilayer itself will be studied by fast photoelectric methods and by the photogating effect developed during previous studies. These methods allow direct measure of kinetics on the subnanosecond time scale. The photogating method uses photogeneration of charge within the membrane and allows ion movement to be observed without interfering capacitative artefacts. These measurements and electrostatic calculations of interactions within the membrane will be used to disentangle the various stages of charge movement: interfacial, transmembrane,and reverse interfacial. We will use the fullerence C60 as a novel hydrophobic anion charge carrier. In particular we will aim at verifying our Ion Chain hypothesis of hydrophobic ion conductance across bilayers. A chain of alternating cations and anions may allow an ion to cross the membrane by a single hop at each end, analagous to the Grotthuss mechanism for excess proton or hydroxyl ion mobilities in water. Proof of this mechanism would have implications for the origin of ion channels: the Ion Chain can be looked upon as a prototype of these channels. Synthesis of analogues of channel forming peptides such as cecropins and melittins will be used to understand the molecular determinants of channel formation and of ion gating. The methodology of wide band, time resolved, pulsed photoacoustics developed during previous studies, will be applied to bacteriorhodopsin and to charge transfer reactions in solution and at interfaces. A major aim will be to ascertain the importance of entropic effects or "conformational changes" in bacteriorhodopsin and of solvation effects in charge transfer reactions.

这项研究的目的是加深我们对电荷的理解 跨生物界面的转移，一个对所有生物都至关重要的过程 细胞。 平面脂质双层被用作细胞间的模型 面孔。 电荷在脂质双层-水界面上的转移 将通过快速光电方法研究双层本身 以及之前研究中开发的光电门控效应。 这些 方法允许在亚纳秒时间尺度上直接测量动力学。 光门控方法利用膜内电荷的光生作用 并允许在不干扰电容的情况下观察离子运动 文物。 这些测量和静电计算 膜内的相互作用将被用来解开各种 电荷运动的阶段：界面、跨膜和反向 界面。 我们将使用富勒 C60 作为新型疏水性阴离子 电荷载体。 我们特别致力于验证我们的离子链 跨双层疏水离子电导的假设。一条链 交替的阳离子和阴离子可能允许离子穿过膜 在每一端通过一个单跳，类似于 Grotthuss 机制 水中过量的质子或氢氧根离子迁移率。 证明这一点 机制将对离子通道的起源产生影响：离子 Chain可以被视为这些渠道的原型。 通道形成肽（例如天蚕素）类似物的合成 蜂毒肽将用于了解其分子决定因素 通道形成和离子门控。 宽带时间分辨脉冲光声学方法 在之前的研究中开发的，将应用于细菌视紫红质 以及溶液中和界面处的电荷转移反应。 一个专业 目的是确定熵效应的重要性或 细菌视紫红质的“构象变化”和溶剂化效应 在电荷转移反应中。