New Synthesis of Polypeptides by Enzyme Systems Cotrolled by Chemical and Physical Methods

多肽具有多种功能，主要取决于其一级结构，即氨基酸序列。对于氨基酸的有序聚合，生物催化剂的利用是可取的，但一般来说，利用生物特异性催化剂（如酶）的尝试本质上受到催化剂的自然特性的限制，并且通常无法制备全新的物质。在多肽合成中通常使用两种类型的生物催化，即蛋白酶的反催化，其中适用于一种酶的多肽的变化是有限的，以及使用DNA-mRNA模板的体外蛋白质合成系统，无法合成非天然多肽。为了克服这些问题，本研究项目旨在通过对蛋白质进行化学和生化改性，并在这些酶催化反应中应用高度极端的物理条件来创建新的酶系统。这是;对热溶酶和丝氨酸羧肽酶进行修饰，并在高压、高盐浓度或高有机溶剂含量条件下进行蛋白质缩合反应。研究了压力和有机溶剂对氨基酰基trna合成酶失活的影响。

Polypeptides have wide variety of functions, which primarily depends on the 1st order structure, amino acid sequence. For the ordered polymerization of amino acids utilization of biocatalysts is preferable but, in general, attempts of utilization of bio-specific catalysts such as enzymes are inherently limited by the natural character of the catalysts and often powerless for the preparation of completely new substances.In peptide synthesis usually two types of biocatalysis are used, namely reverse catalysis of proteases, in which variation of peptides applicable for one type of enzyme is limited, and in-vitro protein synthetic system using DNA-mRNA template, which is incapable to the synthesis of non-natural peptides.To overcome these points, this research project aimed to create new enzymatic system by using chemical and biochemical modification of the protein and also by applying highly extreme physical conditions on these enzyme catalytic reactions. That is; thermolysin and serine carboxypeptidases were modified and used for the protein condensation and the reactions were performed under high pressure, high salt concentration or high organic solvent content. Effects of pressure and organic solvent on misactivation by amino acyl-tRNA synthetase was also investigated.