SHV型β内酰胺酶抑酶效应的研究

Study of inhibitory activity of SHV type β-lactamases

目的 :采用分光光度法研究革兰阴性菌产生的 4种SHV型 β内酰胺酶的抑酶效应。方法 :分别以L B作图法求取米氏常数 (Km)和最大反应速度 (Vmax) ,以Dixon作图法求取抑制常数 (Ki)。结果 :SHV 2 ,4 ,5对头孢噻肟有水解作用 ,Km 分别为5,4 ,8μmol·L- 1,相对最大水解速度分别为 4 .9% ,8.4 % ,7.8%。表明头孢噻肟对SHV 2 ,SHV 4 ,SHV 5有较高的亲和力 (低Km) ,它对SHV 2 ,SHV 4 ,SHV 5有抑制作用 ,Ki 分别为 0 .94 ,1.0 9,1.4 7μmol·L- 1。结论 :β内酰胺酶抑制剂舒巴坦对SHV 1,2 ,4 ,5均有抑制作用 ,Ki 分别为 1.68,0 .2 ,2 .33,0 .15μmol·L- 1。

AIM: To study spectrophotometrically the inhibitory activity of 4 SHV types β lactamases extracted from gram negative bacteria. METHODS: Michaelis constant ( K m) and maximal velocity ( V max ) were obtained from L B plot, inhibition constant ( K i) was obtained from Dixon plot. RESULTS: cefotaxime was hydrolyzed by SHV 2,4,5 enzyme, K m was 5,4,8 μmol·L -1 ; V max was 4.9% ,8.4%,7.8% respectively. It was demon strated that cefotaxime had a high affinity to SHV 2,SHV 4,SHV 5, it had some inhibitory action on SHV 2,SHV 4,SHV 5. K i was 0.94,1.09,1.47 μmol·L -1 separately. CONCLUSION: The β lactamases inhibitor, sulbactam, exhibited inhibitory activity against 4 SHV types β lactamases (SHV 1,2,4,5) K i is 1.68,0.2,2.33,0.15 μmol·L -1 in turn.