ELECTROSTATIC POTENTIALS AND BIOLOGICAL MEMBRANES

长期目标是描述静电和 生物膜的电动特性。一共有六个 具体目标：(一)调查指控的离散性 使用正膜和负膜的效果，多价 以及单价脂类，以及冷冻和流体双层； (Ii)测量多价脂的相互作用(例如， 磷脂酰肌醇4，5-二磷酸，PIP2)与 在膜溶液附近有几个正电荷 界面(例如，血糖素、蜂毒素、视紫红质)； 确定离表面1 nm处的静电势 带电薄膜；(Iv)研究静电和 模型膜和生物膜的电动特性 它们的电荷与膜相距很远- 溶液界面；(V)研究其离子交换性质 PIP2；(Vi)评估静电势在 胞吐。已建立的实验技术将用于 测量：平面双层膜的电导，表面 单分子膜的电势、声化产物的31P核磁共振谱 小泡，小泡的荧光(来自探针TNS)，以及 脂泡和生物膜的电泳率 膜。将开发一种新的荧光技术； 荧光探头将固定在指定的位置 神经节苷脂，荧光被阳离子猝灭 坦帕胺或铊，以及从 玻尔兹曼关系。所有这些技术的结果都将 与经典理论的预测相比较(要么是 古伊-斯托克斯方程)，并用现代的 统计力学理论由S.Marcelja发展，他将 在此项目上进行协作。实验结果，以及 这些结果将产生的理论概念是 与健康相关，因为PIP2是两秒的来源 细胞内的信使和神经节苷脂参与细胞-细胞 承认。例如，具有高亲和力的抗体 神经节苷脂GD3最近被证明对 黑色素瘤的治疗。关于生物物理的信息 因此，人们应该对PIP2和神经节苷脂的性质感兴趣 许多生理学家、生物化学家、细胞生物学家和临床医生。

The long-term objective is to describe the electrostatic and electrokinetic properties of biological membranes. There are six specific aims: (i) to investigate the discreteness-of-charge effect using positive as well as negative membranes, polyvalent as well as monovalent lipids, and frozen as well as fluid bilayers; (ii) to measure the interaction of polyvalent lipids (e.g., phosphatidylinositol 4, 5-bisphosphate, PIP2) with proteins that have several positive charges close to the membrane-solution interface (e.g., glycophorin, melittin, rhodopsin); (iii) to determine the electrostatic potential 1 nm from the surface of a charged membrane; (iv) to investigate the electrostatic and electrokinetic properties of model and biological membranes that have charges a significant distance from the membrane- solution interface; (v) to study the ion exchange properties of PIP2; (vi) to evaluate the role electrostatic potentials play in exocytosis. Established experimental techniques will be used to measure: the conductance of planar bilayers, the surface potential of monolayers, the 31P NMR spectra of sonicated vesicles, the fluorescence (from the probe TNS) of vesicles, and the electrophoretic mobility of both lipid vesicles and biological membranes. A new fluorescence technique will be developed; fluorescent probes will be attached to defined locations on gangliosides, the fluorescence quenched with the cations tempamine or thallium, and the potential estimated from the Boltzmann relation. The results from all these techniques will be compared with the predictions of classical theories (either the Gouy-Stokes equations) and with the predictions of a modern statistical mechanical theory developed by S. Marcelja, who will collaborate on this project. The experimental results, and theoretical concepts that will emerge from these results, are health related because PIP2 is the source of two second messengers in the cell and gangliosides are involved in cell-cell recognition. For example, an antibody with a high affinity for the ganglioside GD3 has recently been shown to be effective in the treatment of melanomas. Information about the biophysical properties of PIP2 and gangliosides should thus be of interest to many physiologists, biochemists, cell biologists and clinicians.