Guo Lin, Lu Zhi-Rong, Park Daeui, Oh Sang Ho, Shi Long, Park Seong Jin, Bhak Jong, Park Yong-Doo, Ren Zhen-Long, Zou Fei
College of Life Science and State Key Laboratory for Plant Genetics and Breeding, Sichuan Agricultural University, Sichuan 625014, PR China.
J Biomol Struct Dyn. 2008 Dec;26(3):395-402. doi: 10.1080/07391102.2008.10507254.
We found that the histidine chemical modification of tyrosinase conspicuously inactivated enzyme activity. The substrate reactions with diethylpyridinecarbamate showed slow-binding inhibition kinetics (KI = 0.24 +/- 0.03 mM). Bromoacetate, as another histidine modifier, was also applied in order to study inhibition kinetics. The bromoacetate directly induced the exposures of hydrophobic surfaces following by complete inactivation via ligand binding. For further insights, we predicted the 3D structure of tyrosinase and simulated the docking between tyrosinase and diethylpyridinecarbamate. The docking simulation was shown to the significant binding energy scores (-3.77 kcal/mol by AutoDock4 and -25.26 kcal/mol by Dock6). The computational prediction was informative to elucidate the role of free histidine residues at the active site, which are related to substrate accessibility during tyrosinase catalysis.
我们发现，酪氨酸酶的组氨酸化学修饰显著降低了酶活性。与二乙基吡啶氨基甲酸盐的底物反应呈现慢结合抑制动力学（KI = 0.24 +/- 0.03 mM）。作为另一种组氨酸修饰剂的溴乙酸盐也被用于研究抑制动力学。溴乙酸盐直接诱导疏水表面的暴露，随后通过配体结合完全失活。为了进一步深入了解，我们预测了酪氨酸酶的三维结构，并模拟了酪氨酸酶与二乙基吡啶氨基甲酸盐之间的对接。对接模拟显示出显著的结合能分数（AutoDock4为-3.77 kcal/mol，Dock6为-25.26 kcal/mol）。该计算预测有助于阐明活性位点游离组氨酸残基的作用，这些残基与酪氨酸酶催化过程中的底物可及性有关。
