Rules for Helix Intiation, Propagation, and Termination

描述（由申请人提供）：本研究项目的长期目标是了解蛋白质稳定性机制的详细物理化学基础。蛋白质的功能需要将线性多肽序列编码的信息翻译成特定的三维结构。蛋白质的功能、结构和稳定性之间的关系是复杂的。微小的扰动，如单位点突变，可以改变蛋白质的功能、运输、降解率或溶解度，导致细胞异常，在某些情况下，是致命的。然而，蛋白质也具有很大程度的可塑性，有大量的氨基酸突变并不影响整体的结构或功能。了解序列、结构和稳定性之间的关系不仅对加深对生物系统的理解至关重要，而且对开发合理设计新蛋白质结构和增强生物活性蛋白质稳定性的方法也至关重要。这可以用于改善人类福祉和健康的生物技术。目前的研究计划旨在了解氨基酸序列如何决定α -螺旋片段的稳定性和特异性，无论是在溶液中还是在蛋白质结构内，并确定蛋白质稳定性的普遍和特殊决定因素。需要回答的四个大问题是：(1)。a型螺旋n端稳定的机理是什么？(2)。主构象和c端氢键对a-螺旋稳定性的贡献是什么？(3)。螺旋-线圈转变的焓对螺旋倾向量表的贡献是什么？(4)。螺旋-线圈转换对蛋白质-蛋白质相互作用的能量学有何贡献？为了回答这些问题，实验，包括位点定向诱变，量热法，荧光，圆二色性和核磁共振光谱，以及计算方法，将应用于模型蛋白泛素，人胰腺多肽，钙调素和S100P，以及短单肽。

DESCRIPTION (provided by applicant): The long-term goal of this research program is to understand the detailed physico-chemical basis for the mechanism of protein stability. The function of proteins requires translation of the information encoded by a linear polypeptide sequence into a specific three-dimensional structure. The relationship between protein function, structure and stability is complex. Small perturbations such as single-site mutations can alter protein function, trafficking, degradation rate or solubility, leading to cellular abnormalities that, in some cases, are lethal. However, proteins also possess a great degree of plasticity and there are large number of amino acid mutations that do not affect the overall structure or function. The knowledge of the relationship between sequence, structure and stability is critical for, not only a deeper understanding of biological systems, but also for the development of approaches that allow rational design of new protein structures and enhanced stabilities of biologically active proteins. This can be used in biotechnology for improving human well-being and health. The present research proposal aims to understand how the amino acid sequence determines the stability and specificity of alpha-helical segments, both in solution and within protein structure, and to identify the universal and specialized determinants for protein stability. The four broad questions to be answered are: (1). What is the mechanism of stabilization of the N-termini of a-helices? (2). What is the contribution of the backbone conformation and hydrogen bonding at the C-terminus to the stability of the a-helix? (3). What is the contribution of the enthalpy of helix-coil transition to the helix propensity scale? (4). What is the contribution of helix-coil transition to the energetics of protein-protein interactions? To answer these questions, experiments, that include site-directed mutagenesis, calorimetry, fluorescence, circular dichroism and NMR spectroscopies, and computational approaches, will be applied to the model proteins ubiquitin, human pancreatic polypeptide, calmodulin and S100P, and short monomeric peptides.