Yang Feifei, Chu Wangsheng, Yu Meijuan, Wang Yu, Ma Sixuan, Dong Yuhui, Wu Ziyu
Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People's Republic of China.
J Synchrotron Radiat. 2008 Mar;15(Pt 2):129-33. doi: 10.1107/S0909049507064126. Epub 2008 Feb 19.
Imidazolonepropionase is an important enzyme that plays a crucial role in the degradation of the histidine in mammals and bacteria. In this contribution a detailed structural investigation is presented of the imidazolonepropionase from Bacillus subtilis at the zinc site by X-ray absorption near-edge structure (XANES) spectroscopy combining experimental data with ab initio calculation in the framework of the multiple-scattering theory. The resolved local structure leads to a modification of the data set in the Protein Data Bank (PDB) (PDB code 2BB0). Actually, data suggest that the carboxyl of the Asp324 moves far away from the zinc ion at the center, while the water molecule and the nearest-neighbor histidines move towards it. This new conformation and the occurrence of a short water-to-zinc bond length support the nucleophilic attack catalytic mechanism proposed for this enzyme.
咪唑啉酮丙酸酶是一种重要的酶，在哺乳动物和细菌体内组氨酸的降解过程中发挥着关键作用。本文通过X射线吸收近边结构（XANES）光谱，结合多散射理论框架下的从头计算实验数据，对枯草芽孢杆菌中的咪唑啉酮丙酸酶在锌位点进行了详细的结构研究。解析出的局部结构导致蛋白质数据库（PDB）（PDB代码2BB0）中的数据集发生了修改。实际上，数据表明，Asp324的羧基远离中心的锌离子，而水分子和最近邻的组氨酸则向其靠近。这种新的构象以及短的水-锌键长的出现，支持了该酶的亲核攻击催化机制。
