Rules for Helix Intiation, Propagation, and Termination

描述(申请人提供)：该研究计划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。像单点突变这样的小干扰会改变蛋白质的功能、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，存在大量不影响整体结构或功能的氨基酸突变。对序列、结构和稳定性之间关系的了解不仅对于加深对生物系统的理解至关重要，而且对于开发能够合理设计新的蛋白质结构和提高生物活性蛋白质稳定性的方法也是至关重要的。这可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-螺旋片段在溶液中和蛋白质结构中的稳定性和特异性，并确定蛋白质稳定性的通用和特殊决定因素。需要回答的四个主要问题是：(1)。α-螺旋的N-末端稳定的机制是什么？主链构象和C末端的氢键对a-螺旋的稳定性有什么贡献？(3)螺旋-线圈的转变热对螺旋倾向标度的贡献是什么？螺旋-螺旋转变对蛋白质-蛋白质相互作用的能量学有什么贡献？为了回答这些问题，包括定点突变、量热、荧光、圆二色谱和核磁共振光谱以及计算方法在内的实验将应用于模型蛋白质泛素、人胰腺多肽、钙调素和S100P以及短单体多肽。

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.