Kazuyo Fukura, Hong So Yeon, Yeon Young Joo, Joo Jeong Chan, Yoo Young Je
Graduate Program of Bioengineering, Seoul National University, Seoul, 151-742, Republic of Korea.
J Ind Microbiol Biotechnol. 2014 Aug;41(8):1181-90. doi: 10.1007/s10295-014-1454-z. Epub 2014 May 22.
Enzymes undergo multiple conformational changes in solution, and these dynamics are considered to play a critical role in enzyme activity. Hinge-bending motions, resulting from reciprocal movements of dynamical quasi-rigid bodies, are thought to be related to turnover rate and are affected by the physical properties of the hinge regions. In this study, hinge identification and flexibility modification of the regions by mutagenesis were conducted to explore the relationship between hinge flexibility and catalytic activity. Bacillus circulans xylanase was selected for the identification and mutation of the hinge regions. As a result, turnover rate (V(max)) was improved approximately twofold in mutants that have more rigid hinge structure, despite the decrease in K(m) and V(max)/K(m). This result indicates that the rigidly mutated hinge has positive effects on B. circulans xylanase activity.
酶在溶液中会经历多种构象变化，这些动力学变化被认为在酶活性中起着关键作用。由动态准刚体的相互运动引起的铰链弯曲运动被认为与周转率有关，并受到铰链区域物理性质的影响。在本研究中，通过诱变进行铰链识别和区域柔韧性修饰，以探索铰链柔韧性与催化活性之间的关系。选择环状芽孢杆菌木聚糖酶进行铰链区域的识别和突变。结果，尽管米氏常数（K(m)）和最大反应速度比（V(max)/K(m)）降低，但具有更刚性铰链结构的突变体的周转率（V(max)）提高了约两倍。该结果表明，刚性突变的铰链对环状芽孢杆菌木聚糖酶活性具有积极影响。
