Anesthetic Effects on Ion Channel Structures & Dynamics

对离子通道结构的麻醉作用

• 批准号: 6640417
• 负责人: PEI TANG
• 金额: $ 23.65万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2006-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6640417
• 关键词: anesthetics; computer simulation; cyclic compound; drug interactions; drug screening /evaluation; general anesthesia; glycine receptors; gramicidin; halothane; intermolecular interaction; ion transport; ligands; membrane channels; molecular dynamics; nuclear magnetic resonance spectroscopy; parallel processing; pharmacokinetics; protein protein interaction; protein structure function; receptor binding; thermodynamics

The molecular mechanisms of general anesthesia remain unknown. The goal of the proposed studies is to elucidate the important role of ion channel dynamics in the action of volatile anesthetics. Guided by our experimental results, mostly from NMR spectroscopy, we will use large-scale molecular dynamics (MD) simulations to investigate changes in transmembrane channel dynamics due to interaction with anesthetics and nonanesthetics (nonimmobilizers), which are structurally similar to the anesthetics but are peculiarly devoid of any anesthetic effects. Two model channels chosen for this study are gramicidin A (gA) and a homopentameric channel complex composed of the second and third transmembrane domains of the alpha-1 subunits of human glycine receptor (GlyR). The NAMD2 program, developed at the University of Illinois, will be used for parallel computing. The specific aims are: (1) to determine the structures and properties of fluorinated volatile anesthetic and nonanesthetic molecules by ab initio quantum mechanics and MD calculations, and to simulate ion channel dynamics up to 10 ns in fully hydrated membrane systems containing linear and cyclic anesthetics and nonanesthetics; (2) to study the steered ion transport effects on the changes in channel dynamics due to anesthetics and, conversely, to qualitatively analyze the anesthetic-induced changes in the steering force; (3) to investigate the channel dynamics responses to the steered gating movement of the GlyR TM2+TM3 channel in the presence and absence of anesthetic- nonanesthetic pairs; (4) to determine GlyR channel dynamics response to the forced binding and unbinding of anesthetics at the critical anesthetic-sensitive mutation site, S267, in the TM2 of GlyR; and (5) for all the simulation results in Specific Aims 1-4, to quantify the channel and lipid dynamics by analyzing root-mean-square deviation (RMSD) and fluctuations (RMSD), the autocorrelation functions, and generalized order parameters (S2), and to investigate the effects of interfacial water, interfacial lipids, and cavity dynamics on anesthetic-induced changes in channel dynamics. The central hypothesis to be tested is that anesthetics affect transmembrane channel function by profoundly changing the channel dynamics and the channel's association with lipids and interfacial water. The results from the proposed study will significantly advance the science in the following three areas: (1) large-scale parallel computing applications to biological problems, particularly anesthetic interaction with membrane-associated proteins; (2) detailed elucidation of residual dynamic contribution (through conformational entropy change) to the interfacial association between lipids and transmembrane channels; and (3) the development of a protein theory of general anesthesia on the basis of dynamics-function relationships.

全身麻醉的分子机制仍不清楚。 拟议研究的目标是阐明离子通道动力学在挥发性麻醉剂作用中的重要作用。 我们的实验结果的指导下，主要是从NMR光谱，我们将使用大规模的分子动力学（MD）模拟研究跨膜通道动力学的变化，由于与麻醉剂和非麻醉剂（nonimmobilizer），这是结构上类似的麻醉剂，但特别是没有任何麻醉效果的相互作用。本研究选择的两个模型通道是短杆菌肽A（gA）和由人甘氨酸受体（GlyR）α-1亚基的第二和第三跨膜结构域组成的同源五聚体通道复合物。 NAMD 2计划由伊利诺伊大学开发，将用于并行计算。 具体目标是：（1）通过从头算量子力学和分子动力学计算确定氟化挥发性麻醉剂和非麻醉剂分子的结构和性质，并在含有线性和环状麻醉剂和非麻醉剂的完全水合膜系统中模拟高达10 ns的离子通道动力学;（2）研究由于麻醉剂引起的操纵离子运输对通道动力学变化的影响，反之，定性分析麻醉诱导的操纵力的变化：（3）研究在存在和不存在麻醉-非麻醉对的情况下GlyR TM 2 + TM 3通道对操纵门控运动的通道动力学响应;（4）在GlyR的TM 2关键的麻醉药敏感突变位点S267处，测定GlyR通道对麻醉药强制结合和解除结合的动力学响应;以及（5）对于特定目标1-4中的所有模拟结果，通过分析均方根偏差（RMSD）和波动（RMSD）来量化通道和脂质动力学，的自相关函数，和广义序参数（S2），并调查的影响，界面水，界面脂质，腔动力学麻醉诱导的通道动力学的变化。 要测试的中心假设是，麻醉剂影响跨膜通道功能，深刻地改变通道动力学和通道的协会与脂质和界面水。 该研究的结果将在以下三个领域显着推进科学：（1）大规模并行计算应用于生物学问题，特别是麻醉剂与膜相关蛋白的相互作用;（2）详细阐明剩余动力学贡献（通过构象熵变）到脂质和跨膜通道之间的界面缔合;（3）在动力学-功能关系的基础上发展了全身麻醉的蛋白质理论。