PROTEIN STABILITY--CATALYTIC AND NONCATALYTIC SOLVENTS

蛋白质稳定性——催化和非催化溶剂

• 批准号: 3308432
• 负责人: TIMOTHY A CROSS
• 金额: $ 11.76万
• 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/3308432
• 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。 我们对细胞质蛋白的了解是 不适合这种考虑。 静电相互作用， 特别是氢键在这些力中所起的作用越来越大 相对于细胞质， proteins. 这是用肽-肽和肽- 溶剂相互作用 溶剂在这些相互作用中的作用是 在此称为非催化作用。 同时，氢 键对于通过催化构象的相互转化是至关重要的 氢键的交换，因此对溶剂有催化作用。 在这项研究中，我们建议证明和表征这些作用， 通过对十五肽短杆菌肽A（gA）在 有机溶剂和脂质双层中。ga有许多稳定的 有机溶剂中的构象，将详细研究， 溶液NMR方法。 在某些有机溶剂中， 构象可以被捕获，即它们不相互转化，并且如果它们 最小能量构象是否会与 困住了 在其他能提供氢键的溶剂中， 易于相互转换。 在脂双层中，gA可以以构象存在 除了沟道状态，即脂质双层也可以捕获非- 多肽的最小能量构象。 这一点非常重要 蛋白质和多肽活性调节的意义 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所不知道的溶剂水的催化作用 和非催化作用的脂质将其特征在于根据 在有机溶剂中的结构重排（溶液NMR）和在 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， 构象互变以及多肽的稳定性 在膜环境中。