葡萄糖激酶M197V突变的活化机理研究

Activation Mechanism Study of Glucokinase by M197V Mutation

葡萄糖激酶(glucokinase,GK)催化葡萄糖转变为6-磷酸葡萄糖,是糖代谢的第一步,所以GK活性异常在糖代谢紊乱的发生发展中起着重要作用.对青年型早发糖尿病(maturity-onset diabetes of the young 2,MODY 2)型和高胰岛素性低血糖症(persistent hyperinsulinemic hypoglycemia of infancy,PHHI)型的深入研究证实了GK活性改变与糖尿病的发生有关.为了研究GK活性改变的机理,通过分子动力学模拟和隐性溶剂的自由能的计算对GK的单点突变M197V(Met197→Val)进行了理论研究.通过GK的Cα原子均方根浮动变化(Root mean square fluctuation,RMSF)和动态相关性矩阵(Dynamic cross-correlation matrices,DCCM)分析,显示M197V突变导致GK在活化状态的构象更加稳定.通过包结自由能分析,表明M197V突变可以增加GK对葡萄糖的包结亲合性,并且理论预测突变前后的相对包结自由能差值和已有的实验结果非常吻合.研究结果很好地从原子水平解释了GK的M197V突变的活化机理.

Glucokinase （GK） is a glycolic enzyme that catalyzes the phosphorylation of glucose to glucose-6-phosphate in the first step of glycolysis. Thus alteration in GK activity plays an important role in abnormal glycemia. A great deal of research about maturity-onset diabetes of the young 2 （MODY 2） and persistent hyperinsulinemic hypoglycemia of infancy （PHHI） confirmed that the change of GK activity was associated with diabetes. The explicit molecular dynamics simulations and implicit solvent binding free-energy calculations were investigated to understand the activation mechanism of OK point mutation M197V （Met^197 →Val）. The root mean square fluctuation （RMSF） and dynamic cross-correlation matrices （DCCM） conformation analysis showed that GK M197V mutation resulted in a more stable active conformation. The binding free-energy analysis demonstrated that the GK M197V mutation increased its binding affinity with glucose. The difference of binding free-energy between wild-type （WT） GK and M197V GK was in well agreement with previous experimental results. Our results can interpret the active mechanism of GK M197V mutation from the atom level perfectly.