PROTEIN STABILITY--CATALYTIC AND NONCATALYTIC SOLVENTS

蛋白质稳定性——催化和非催化溶剂

• 批准号: 2186628
• 负责人: TIMOTHY A CROSS
• 金额: $ 11.46万
• 依托单位: FLORIDA STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-08-01 至 1996-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2186628
• 关键词: benzene; chemical group; chemical stability; conformation; dioxins; ethanol; hydrogen bond; hydropathy; intermolecular interaction; ionic bond; lipid bilayer membrane; membrane channels; membrane proteins; molecular dynamics; molecular rearrangement; nuclear magnetic resonance spectroscopy; peptide analog; peptide chemical synthesis; peptide structure; solvents; synthetic peptide; thermodynamics

The stability of polypeptide and protein conformation in membranes is not well understood. Our knowledge from cytoplasmic proteins is inappropriate for this consideration. Electrostatic interactions and, in particular, hydrogen bonds play a much increased role among the forces that stabilize peptide conformations in membranes relative to cytoplasmic proteins. This is accomplished with both peptide - peptide and peptide - solvent interactions. The role of the solvent in these interactions is referred to here as the non-catalytic role. At the same time hydrogen bonds are critical for the interconversion of conformations by catalyzing the exchange of hydrogen bonds, hence a catalytic role for solvent. In this study we propose to demonstrate and characterize these roles for the solvent via studies of the pentadecapeptide, gramicidin A (gA) in both organic solvents and in lipid bilayers. gA has numerous stable conformations in organic solvents that will be studied in detail by solution NMR methods. In some organic solvents a variety of these conformations can be trapped, i.e. they don't interconvert and if they did the minimum energy conformer would be different from the one that is trapped. In other solvents that can donate hydrogen bonds the conformers readily interconvert. In lipid bilayers gA can exist in conformations other than the channel state, i.e. the lipid bilayer can also trap non- minimum energy conformations of a polypeptide. This has very significant implications for the regulation of protein and polypeptide activity in membranes. Is there, in fact, a mechanism for protein regulation that we as biochemists are not aware of? The catalytic role of solvent water and non-catalytic role of lipid will be characterized in light of structural rearrangements both in organic solvents (solution NMR) and in a lipid environment (solid state NMR). The prime goals are to learn more about the role of solvent in hydrophobic polypeptide conformation and conformational interconversion as well as the stability of polypeptides in membrane environments.

膜中多肽和蛋白质构象的稳定性不是 很好理解。我们对细胞质蛋白质的了解是 对于这种考虑是不合适的。静电相互作用和， 特别是，氢键在作用力中的作用要大得多。 稳定细胞膜上相对于细胞质的多肽构象 蛋白质。这是通过多肽-多肽和多肽- 溶剂相互作用。溶剂在这些相互作用中的作用是 这里指的是非催化作用。同时，氢气 键是催化构象相互转化的关键 氢键的交换，因此对溶剂有催化作用。 在这项研究中，我们建议演示和描述这些角色 十五肽甘草素A(GA)的溶剂研究 无论是有机溶剂还是脂类双层。GA有众多的稳定 有机溶剂中的构象将由 溶液核磁共振方法。在一些有机溶剂中，有各种这样的 构象可以被捕获，即它们不会相互转换，如果它们 最低能量构象会不会与 被困住了。在其他可以提供氢键的溶剂中，异构体 很容易相互转换。在脂质双层中，Ga可以以构象的形式存在 除通道状态外，即脂双分子层也可以捕获非 多肽的最小能量构象。这具有非常重要的意义 蛋白质和多肽活性调控的意义 膜。事实上，有没有一种蛋白质调节机制 我们作为生物化学家难道不知道吗？溶剂水的催化作用 而脂质的非催化作用将根据以下方面进行表征 有机溶剂(溶液核磁共振)和In中的结构重排 脂质环境(固态核磁共振)。主要目标是了解更多信息 关于溶剂在疏水多肽构象中的作用和 多肽的构象相互转化及其稳定性 在膜环境中。