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Elucidation of the Mechanisms of Induced-fit Movement imposed on Enzymes and Substrates as studied by Precise Crystal Structure Analysis.

通过精确晶体结构分析研究，阐明酶和底物的诱导配合运动机制。

基本信息

批准号：
60580128
负责人：
MITSUI Yukio
金额：
$ 0.83万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1986
项目状态：
已结题

项目摘要

Regarding a microbial proteinase "Subtilisin" and its substrate (actually proteinaceous inhibitor) "SSI"(Streptomyces Subtilisin Inhibitor), the followings have been achieved or elucidated.1) Resolution of the crystal structure analysis of free SSI was raised to 1.85 <ang> (from 2.6 <ang> ).2) Resolution of the crystal structure analysis of SSI-Subtilisin complex was raised to 2.0 <ang> (from 2.6 <ang> ).3) Making use of the results of 1) and 2), the detailed nature of the conformational change imposed on the enzyme Subtilisin and the substrate SSI upon complex formation was analyzed. For this analysis, the newly devised "Difference Distance Map" and the "Relative Difference Distance Map" were fully made use of. 3A) The global structure of the enzyme Subtilisin is virtually unchanged after complex formation with the substrate SSI, although some local induced-fit movement does occur. 3B) The substrate SSI undergoes global conformational change upon complex formation with the enzyme Subtilisin in the way described below. a) No conspicuous conformational changes occur within any local structure formed by 10 consecutive amino acid residues, b) no <alpha> -helices per se undergoes any significant conformational change, c) no conspicuous changes occur in the relative disposition of any two neighbouring <beta> -strands, d) the <alpha_1> -helix is separated from the <beta_1> - and <beta_2> -strands by ca. 2 <ang> . 3C) The mechanism of conformational change described in 3B) above is unique in the light of the two well-known mechanisms, the "hinge bending mechanism" and the "helix shear mechanism".

关于微生物蛋白酶“枯草杆菌蛋白酶”及其底物（实际上是蛋白质抑制剂）“SSI”（链霉菌枯草杆菌蛋白酶抑制剂），已经实现或阐明了以下内容：1）游离SSI的晶体结构分析的分辨率提高到1.85<ang>（从2.6<ang>）。2）SSI-枯草杆菌蛋白酶复合物的晶体结构分析的分辨率提高到2.0<ang>（从2.6<ang>）。3）利用1）和2）的结果，分析了复合物形成时施加在酶枯草杆菌蛋白酶和底物SSI上的构象变化的详细性质。本次分析充分利用了新设计的“差异距离图”和“相对差异距离图”。3A）在与底物SSI形成复合物后，酶枯草杆菌蛋白酶的整体结构几乎不变，尽管确实发生了一些局部诱导的拟合运动。3B）底物SSI在以下述方式与酶枯草杆菌蛋白酶形成复合物后经历整体构象变化。a）在由10个连续氨基酸残基形成的任何局部结构中没有明显的构象变化，B）<alpha>-螺旋本身没有经历任何明显的构象变化，c）任何两个相邻-链的相对位置没有明显的变化<beta>，d）<alpha_1>-螺旋与<beta_1>-和<beta_2>-链被ca.二<ang>、3C）上述3B）中所述的构象变化机制在两种公知的机制“铰链弯曲机制”和“螺旋剪切机制”方面是独特的。