Flocco M M, Mowbray S L
Department of Molecular Biology, Uppsala University, Sweden.
Protein Sci. 1995 Oct;4(10):2118-22. doi: 10.1002/pro.5560041017.
A simple method is presented for the analysis of protein conformational changes based on the comparison of torsion angles defined by four consecutive C alpha atoms. The technique was applied successfully to proteins that undergo hinge motion and shear motion. In the case of both MBP and LAO, which represent examples of hinge motion, the plot of the differences in C alpha-torsion angles between the open and closed forms of the proteins helped us to formulate a more thorough description of the conformational change: a large displacement of one domain with respect to the other where one of the domains does not behave like a rigid body but exhibits some degree of flexibility. The analysis of citrate synthase, which is an example of shear motion, shows that the largest differences in C alpha-torsion angles between the open and closed conformations are clustered around residues that belong to segments connecting alpha-helices, whereas the helices themselves appear to be rigid; this is in agreement with previous results obtained by detailed least-squares superpositions (Lesk AM, Chothia C, 1984, J Mol Biol 174:175-191).
本文提出了一种基于四个连续Cα原子所定义的扭转角比较来分析蛋白质构象变化的简单方法。该技术已成功应用于经历铰链运动和剪切运动的蛋白质。对于代表铰链运动示例的MBP和LAO而言，蛋白质开放形式与闭合形式之间Cα扭转角差异的绘图有助于我们更全面地描述构象变化：一个结构域相对于另一个结构域有较大位移，其中一个结构域并非像刚体那样表现，而是呈现出一定程度的灵活性。对作为剪切运动示例的柠檬酸合酶的分析表明，开放构象与闭合构象之间Cα扭转角的最大差异集中在属于连接α螺旋片段的残基周围，而螺旋本身似乎是刚性的；这与之前通过详细的最小二乘叠加法获得的结果一致（Lesk AM，Chothia C，1984，J Mol Biol 174：175 - 191）。
