CAJ | 학술논문

环糊精葡萄糖基转移酶(cyclodextrin glycosyltransferase, CGTase, E.C.2.4.1.19)是食品、医药和化妆品等领域中的重要酶。文中通过分子动力学模拟研究了 CGTase 活性位点区域中分子内非共价键相互作用对蛋白质热稳定性的影响，以及在热压力下这些分子内非共价键相互作用又会如何发生变化。研究发现：在 CGTase 酶活性区域中分布着较多的盐桥和氢键网络体系，分析盐桥间的距离变化发现这些盐桥对高温具有很好的抗性，同时，高温下盐桥网络又比单个盐桥更加稳定；对该区域中氢键分析，发现随着模拟温度的升高，带电荷氨基酸之间形成的氢键在高温下具有很好的稳定性，同样，高温下氢键网络也比单个氢键更加稳定；通过对非共价键相互作用的分析中发现活性位点两侧的氨基酸残基与酶的热稳定性也有很大的关系。该蛋白酶的热稳定性与非共价键连接的数量、存在形式及形成非共价键相互作用的氨基酸空间位置都息息相关。该结果为用酶工程设计改造环糊精葡萄糖基转移酶热稳定性提供了突变方向，同时，为理解酶蛋白的热稳定机制，结构与功能关系的研究提供有益参考。
배호정포도당기전이매(cyclodextrin glycosyltransferase, CGTase, E.C.2.4.1.19)시식품、의약화화장품등영역중적중요매。문중통과분자동역학모의연구료 CGTase 활성위점구역중분자내비공개건상호작용대단백질열은정성적영향，이급재열압력하저사분자내비공개건상호작용우회여하발생변화。연구발현：재 CGTase 매활성구역중분포착교다적염교화경건망락체계，분석염교간적거리변화발현저사염교대고온구유흔호적항성，동시，고온하염교망락우비단개염교경가은정；대해구역중경건분석，발현수착모의온도적승고，대전하안기산지간형성적경건재고온하구유흔호적은정성，동양，고온하경건망락야비단개경건경가은정；통과대비공개건상호작용적분석중발현활성위점량측적안기산잔기여매적열은정성야유흔대적관계。해단백매적열은정성여비공개건련접적수량、존재형식급형성비공개건상호작용적안기산공간위치도식식상관。해결과위용매공정설계개조배호정포도당기전이매열은정성제공료돌변방향，동시，위리해매단백적열은정궤제，결구여공능관계적연구제공유익삼고。
Cyclodextrin glucanotransferase (CGTase, EC 2.4.1.19) is an important enzyme in food,pharmaceutical and cosmetic, etc. The objective of this study is to investigate the contribution of non-covalent intramolecular interactions to protein CGTase stability and how changes in these interactions in response to thermal stress. The results show:there are more salt bridge and hydrogen bond network system which distribute in the CGTase enzyme active area. Salt bridge analyses reveals that in one hand, salt bridges involved in active site region are relatively stong at elevated temperature; in the other hand, salt bridge network is more stable than the single salt bridge. Hydrogen bond analyses reveals that the hydrogen bond formed between the charged amino acid has good stability at high temperature, and, hydrogen bond network is more stable than the single hydrogen bond also. Meanwhile, the amino acids, beside the active site, are contributed to the protein thermostability also. These results suggest the protein CGTase stability is related to the number, existent form and amino acid spatial position of the formation of non-covalent interaction. The work provides the direction for mutation to improve enzymatic thermosmbility, furthermore, a useful reference for understanding the mechanism of the thermal stability and structure-function relationship.