Determinants of Fold Stability in Proteins and Analogues

描述（由申请人提供）：我们的研究旨在阐明蛋白质显示的特定折叠和组装行为的起源。蛋白质发挥着对生命至关重要的一系列功能，蛋白质的活性通常取决于多肽链采用的高阶结构。因此，了解控制折叠和组装的因素，即二级、三级和经常是四级结构的形成，对于给定的氨基酸残基序列是一个基本的科学目标。我们的研究采用标准的表征工具；此外，我们努力创造新的工具，为重要问题提供独特的方法。例如，我们正在开发一套新的分子单元，可以对平行β -片二级结构进行热力学分析，目前的一个目标是使用这些工具来阐明诸如链数或链长度等基本参数如何影响平行β -片的稳定性。在这种情况下，我们的独特工具是通过C或n端连接肽段的非天然二胺或二酸片段，并促进水中平行β -片的形成。这样的连接体在经典蛋白质科学中是不可用的，而这项研究需要一个像我们这样在生物物理表征和有机合成方面都有经验的实验室。我们小组最近开发的另一种化学工具，“骨干硫酯交换”（BTE）方法，提供了一种独特的方法来分析小多肽在二级、三级和/或四级结构水平上的序列稳定性相关性。拟议的研究包括使用BTE来探测控制α -螺旋段（例如，卷曲线圈）之间并排相互作用的亲和力和选择性的因素。螺旋-螺旋结合是蛋白质三级和四级结构的一个突出特征，我们的研究将解决这一领域以前未解决的问题。此外，我们建议将BTE扩展到脂质双分子层中螺旋-螺旋相互作用的研究。相对于对溶液中蛋白质的了解，目前对膜中控制蛋白质折叠和结合的力的了解还不充分，而膜蛋白领域的一个主要障碍是缺乏对结构现象进行热力学分析的有效方法。BTE可能是这一领域强有力的新工具。我们希望将我们的理解从蛋白质扩展到具有蛋白质样结构的非天然低聚物。这些努力将扩大对非共价相互作用网络控制柔性低聚物的构象和结合倾向的方式的基本理解。此外，我们研究的这一部分是由长期前景驱动的，即具有良好折叠规则的非天然低聚物可以为创造新型生物医学上有用的药物提供基础。蛋白质是生命的主力分子。蛋白质的功能主要取决于它们所采用的结构，我们工作的一个主要目标是阐明控制蛋白质结构的因素。显示蛋白质样结构行为的非自然分子最终可以被设计成显示生物医学上有用的蛋白质样功能，我们的目标包括发现和表征新的蛋白质模拟系统。

DESCRIPTION (provided by applicant): Our research is intended to elucidate the origins of specific folding and assembly behavior displayed by proteins. Proteins perform a vast array of functions that are essential for life, and protein activity usually depends on the adoption of higher order structure by the polypeptide chain. Therefore, understanding the factors that control folding and assembly, i.e., secondary, tertiary and often quaternary structure formation, for a given sequence of amino acid residues is a fundamental scientific goal. Our research employs standard characterization tools; in addition, we strive to create new tools that offer unique approaches to important questions. For example, we are developing a set of novel molecular units that enable thermodynamic analysis of parallel beta-sheet secondary structure, and one current goal is to use these tools to elucidate how basic parameters such as number of strands or length of strands influence parallel beta-sheet stability. Our unique tools in this case are unnatural diamine or diacid segments that link peptide segments via their C- or N-termini and promote parallel beta-sheet formation in water. Such linkers are not available in classical protein science, and this research requires a laboratory, such as ours, that has experience in both biophysical characterization and organic synthesis. Another chemical tool recently developed by our group, the "backbone thioester exchange" (BTE) method, offers a unique approach to analysis of sequence-stability correlations at secondary, tertiary and/or quaternary structure levels in small polypeptides. The proposed research includes the use of BTE to probe the factors that govern affinity and selectivity in side-by-side interactions between alpha-helical segments (e.g., coiled-coils). Helix-helix association is a prominent feature of protein tertiary and quaternary structure, and our studies will address previously unanswered questions in this area. In addition, we propose to extend BTE to the study of helix-helix interactions in lipid bilayers. Current understanding of the forces that control protein folding and association in membranes is underdeveloped relative to what is known about proteins in solution, and a major stumbling block in the membrane protein field is lack of effective methods for thermodynamic analysis of structural phenomena. BTE could represent a powerful new tool in this field. We want to extend our understanding beyond proteins to unnatural oligomers that display protein-like structures. Such efforts will broaden fundamental understanding of the ways in which networks of noncovalent interactions control the conformations and binding propensities of flexible oligomers. In addition, this component of our research is motivated by the long-term prospect that unnatural oligomers with well-understood folding rules could provide a basis for creating new kinds of biomedically useful agents. PUBLIC HEALTH RELEVANCE Proteins are the workhorse molecules of life. The functions of proteins depend critically on the structures they adopt, and a major goal of our work is to elucidate factors that govern protein structure. Unnatural molecules that display protein-like structural behavior could ultimately be engineered to display biomedically useful protein-like functions, and our goals include the discovery and characterization of new protein-mimetic systems.