Ca^(2+)对α-1,2-甘露糖苷酶活性影响的分子动力学模拟研究

Molecular dynamics simulation on the effects of Ca^(2+) on catalytic performance of α-1,2-mannosidase

采用分子动力学模拟方法讨论了Ca^(2+)对α-1,2-甘露糖苷水解酶(Bt3990)催化性能的影响,以及Bt3990与底物分子的相互作用方式,并测试了删除活性中心Ca^(2+)对酶-底物复合物结构的影响。研究结果表明,当Bt3990活性中心含有Ca^(2+)时酶的体系结构很稳定,同时Ca^(2+)有助于使具有催化功能的残基处于特定的位置,便于其发挥催化作用。Ca^(2+)能促使底物偏离基态构象稳定在近似进攻构象。当Bt3990活性中心失去Ca^(2+)时,酶的体系结构不再稳定。

The effects of Ca^2＋on the catalytic performance of a calcium-containing α-1,2-mannosidase（ Bt3990） were investigated using molecular dynamics simulation.The structural changes of the enzyme-substrate complex in the presence and absence of Ca^2＋in the active site were also discussed.Our simulation indicates that the whole Michaelis system with Ca^2＋can be maintained very well throughout the simulation.The catalytic residues are orientated by Ca^2＋to suitable positions for their catalytic function. The distort conformation of pyranose ring away from its ground-state conformation can be observed with helping of Ca^2＋. The overall structure is unstable without Ca^2＋in the active site,which further highlights the critical role of Ca^2＋in maintaining whole enzyme structure.