BACKBONE EFFECTS ON PROTEIN STABILITY AND FOLDING

本研究计划的目的是了解多肽链的分子结构与其折叠成确定的三维结构的能力之间的关系。了解折叠和稳定性过程的分子基础是生物医学科学的核心，也是分子生物学中尚未解决的基本问题之一。大多数关于蛋白质折叠和稳定性的研究都集中在利用位点定向突变的氨基酸侧链的作用上。我们建议通过使用蛋白质的全合成来化学修饰多肽主链来偏离这一趋势。我们相信，骨干结构的系统性变异将为稳定蛋白质及其折叠过程的基本力量提供新的见解。我们已经证明了化学合成的能力，并将主干修饰引入两个明确定义的蛋白质系统，GCN-4卷曲线圈和糜凝胰蛋白酶抑制剂CI- 2。在这两个系统的背景下，我们计划探索以下相互作用。1)单（- conh -）到（- COO-）在蛋白质螺旋主链中的替换作用。2)“双骨干突变体”周期对α螺旋中局部骨干相互作用的效用。3)利用主链工程肽的组合组装，研究主链修饰对非局部相互作用的影响。4)制造具有蛋白质样折叠特性的所有酯类聚合物的化学可行性。这项工作的长期目标是将仿生和天然产物化学与分子生物学和蛋白质工程领域相结合。蛋白质分子合成化学工具的系统应用将为认识蛋白质功能的分子基础创造一个新的平台。

The objective of this research program is to understand the relationship between the molecular structure of a polypeptide chain and its ability to fold into a defined, three-dimensional structure. Understanding of the molecular basis for the processes of folding and stability is central to biomedical science and represents one of the fundamental unsolved problems in molecular biology. Most studies on protein folding and stability have focused on the role of amino acid sidechains using site-directed mutagenesis. We propose to diverge from this trend by using the total synthesis of proteins to chemically modify the polypeptide backbone. We believe that systematic variation of the backbone will give new insights into the fundamental forces that stabilize proteins and the processes through which they fold. We have demonstrated the ability to chemically synthesize and introduce backbone modifications into two well-defined protein systems, the GCN-4 coiled coil and the chymotrypsin inhibitor CI- 2. In the context of these two systems, we plan to probe the following interactions. 1) The effects of single (-CONH-) to (- COO-) replacements in the backbone of protein helices. 2) The utility of 'double backbone mutant' cycles on the local backbone interactions in alpha helices. 3) The effects of backbone modifications on non-local interactions using the combinatorial assembly of backbone-engineered peptides. 4) The chemical feasibility of creating all ester polymers with protein-like folding properties. The long-term goal of this work is to merge of the fields of biomimetic and natural product chemistry with molecular biology and protein engineering. The systematic application of the tools of synthetic chemistry of protein molecules will create a new platform for the understanding of the molecular basis of protein function.