中文摘要：

目的：在克隆表达肺炎链球菌HMG-CoA合成酶（HMGS）的基础上,对HMGS进行动力学研究。方法：采用紫外分光光度法,以乙酰-CoA作为底物,检测乙酰乙酰-CoA在300 nm处吸收值的变化。结果：肺炎链球菌HMGS的最适pH 9.75、最适温度37℃、最适MgCl2浓度为10 mol/L,粗酶提取物的比活为0.76μmol/min·mg^-1,分离纯化后的比活为3.24μmol/min·mg^-1,比活提高4.26倍。结论：在37℃、pH 9.755、mol/L MgCl2的最适反应条件下,肺炎链球菌HMGS的Vmax和Km值分别为4.69μmol/min·mg^-1和213μmol。

英文摘要：

Objective：The mvaS gene was cloned from S.pneumoniae and expressed in E.coli BL21.The recombinant HMG-CoA synthase（HMGS） was conducted analysis of dynamics and research of function.Methods：Changes of acetoacetyl-CoA were detected in the 300 nm absorption with acetyl-CoA as substrate by UV-Spectrometer.Results：Optimal conditions for recombinant HMGS were pH 9.75 and 10 mol/L MgCl2 at 37℃.The specific activity of the soluble crude extract was 0.76 μmol/min·mg^-1,while it increased to 3.24 μmol/min·mg^-1 after purified by HisTrapTM FF crude 1 ml column.Conclusion：The Vmax and Km were 4.69 μmol/min·mg^-1 and 213 μmol,respectively,under pH 9.75 and 5 mol/L MgCl2 at 37 ℃.