MOLECULAR DYNAMICS AND VIBRATIONAL CHARACTERISTICS OF MEMBRANE ASSEMBLIES

膜组件的分子动力学和振动特性

• 批准号: 6105197
• 负责人: Ira W. Levin
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6105197
• 关键词: Raman spectrometry; biomedical equipment development; biophysics; image processing; infrared spectrometry; interferometry; lipid bilayer membrane; membrane proteins; membrane structure; molecular dynamics; protein biosynthesis; protein structure

Summary of Work: Our research efforts encompassed two general areas: (A) The modulatory effects of bilayer lipids on the structural reorganizations of integral membrane proteins, and (B) the instrumental development and applications of vibrational Raman and infrared spectroscopic imaging techniques. (A) Our interest in characterizing the effects of fluctuating lipid microdomains within biomembranes has recently focused on cluster formation within bilayer matrices comprised of lipid mono- or polyunsaturated sn-2 chain and saturated sn-1 chain assemblies. The lateral compressibility properties of these lipid microaggregates are effective in exerting a modulatory influence on induced conformational changes occurring within integral membrane proteins. In studying spectroscopically specific lipid bilayers, appropriate acyl chain deuteration allows the vibrational dynamics of each chain moiety to be monitored separately. Both Raman and infrared spectroscopic techniques were applied toward examining the bilayer series comprised of 1-eicosanoyl(d39)-2-eicosenoyl-sn-glycero-3-phosphocholine [C(20-d39):C(20:1 delta j)PC, with j=5, 8, 11, and 13]. Established order/disorder parameters pertinent to each chain system were assessed as a function of the placement of the unsaturated chain double bond. Both polycrystalline samples and aqueous bilayer dispersions were examined. Various computational techniques provided estimates of chain cluster sizes, which vary between 3-19 acyl chains for this series of phospholipids. For example, the largest sn-1 chain domain, originating specifically from van der Waals interactions between the chains of neighboring molecules, occurs for the C(20-d39):C(20:1 5)PC species. Using these spectroscopic approaches, we have examined in detail the microheterogeneity of a variety of bilayer assemblies. (B)Emphasis has been placed on enhancing our mid-infrared spectroscopic chemical imaging microscopy techniques by combining step-scan interferometry with state-of-the-art infrared senstive two-dimensional focal plane array detectors. The integration of high performance digital imaging with noninvasive, high resolution optical spectroscopy allows a visualization of the spatial distribution of distinct chemical species in a variety of host environments. The power of the technique is also manifest in the simultaneous acquisition of an infrared spectrum for each spatial location. As an example of the utility of the technique in diagnostic pathology, we applied the infrared imaging methodology to a study of cerebellar tissue from mice presenting the morphology and pathology of Niemann-Pick type C disease. The infrared images provided qualitative descriptions of the biochemical differences between unstained tissue from diseased and control animals. The absorbance images, together with their related spectra, allowed the various cellular layers within the tissue to be identified. Statistical analyses of the individual spectra reflecting the various cellular layers provided concise quantitative descriptions of the observed biochemical variations.

工作总结：我们的研究工作 包括两个一般领域：(A) 双层脂类对整体膜结构重组的影响 蛋白质，以及(B)仪器的开发和应用 振动拉曼和红外光谱成像技术。 (A)我们对描述波动的血脂的影响的兴趣 生物膜中的微域最近关注的是簇合物 在由脂质单链组成的双层基质中的形成 多不饱和SN-2链和饱和SN-1链组件。这个 这些脂质微团聚体的侧向压缩特性为 有效地对诱导产生调制影响 整体膜内的构象变化 蛋白质。在研究光谱特定的脂质双分子层时， 适当的酰基氢化允许振动动力学 每条链的部分要单独监测。拉曼和 红外光谱技术被应用于检测 双层系列包括 1-eicosanoyl(d39)-2-eicosenoyl-sn-glycero-3-phosphocholine [C(20-d39)：C(20：1增量j)pc，其中j=5、8、11和13]。已建立 与每个链系统相关的有序/无序参数是 作为不饱和链放置的函数进行评估 双键。多晶样品和双水分子膜 对分散体进行了考察。各种计算技术 提供了链簇大小的估计，范围在3-19之间 这一系列磷脂的酰基链。例如，最大的 SN-1链状结构域，特别起源于van der Waals 发生在相邻分子链之间的相互作用 C(20-d39)：C(20：15)PC种。使用这些光谱 方法，我们已经详细地研究了一种 各种双层组件。(B)重点放在 增强我们的中红外光谱化学成像 步进扫描干涉技术与显微技术相结合 最新的红外敏感二维焦平面阵列 探测器。高性能数字成像与 非侵入性的高分辨率光学光谱学允许 不同化学物种空间分布的可视化 在各种主机环境中。这项技术的力量在于 也表现在同时获取红外线 每个空间位置的光谱。作为实用程序的一个示例 在病理学诊断技术中，我们应用了红外线 小鼠小脑组织研究的影像方法学 介绍C型Niemann-Pick的形态和病理 疾病。红外图像提供了对 未染色病变组织与非染色组织的生化差异 控制动物。吸光度图像及其相关的 光谱，允许组织内的不同细胞层 确认身份。反映光谱的个体光谱的统计分析 各种细胞层提供了简明的定量描述 观察到的生化变化。