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 理解。 我们来自细胞质蛋白的知识是 不适合此考虑。 静电相互作用， 特别是，氢键在力中起着大大增加的作用 相对于细胞质，稳定膜中的肽构象 蛋白质。 这是通过肽 - 肽和肽 - 溶剂相互作用。 溶剂在这些相互作用中的作用是 这里称为非催化作用。 同时氢气 键对通过催化构象的互换至关重要 氢键的交换，因此是溶剂的催化作用。 在这项研究中，我们建议证明和表征这些角色 通过研究五肽肽gramicidin a（GA）的溶剂 有机溶剂和脂质双层。 GA有许多稳定 有机溶剂中的构象将通过 解决方案NMR方法。 在某些有机溶剂中，各种各样 构象可以被困，即它们不互连，如果它们是否 最低能量构象异构体是否不同于 被困。 在其他可以捐赠氢键的溶剂中 容易互连。 在脂质双层中，ga可以以构象存在 除了通道状态以外，即脂质双层也可以捕获非 - 多肽的最小能量构象。 这很重要 对蛋白质和多肽活性调节的影响 膜。 实际上，是否有一种蛋白质调节的机制 作为生物化学家我们不知道吗？溶剂水的催化作用 脂质的非催化作用将以 有机溶剂（溶液NMR）和 脂质环境（固态NMR）。 主要目标是了解更多 关于溶剂在疏水多肽构象中的作用和 构象相互转换以及多肽的稳定性 在膜环境中。