Substrate specificity of<i>E. coli</i>uridine phosphorylase. Further evidences of high-<i>syn</i>conformation of the substrate in uridine phosphorolysis
作者:C. S. Alexeev、G. G. Sivets、T. N. Safonova、S. N. Mikhailov
DOI:10.1080/15257770.2016.1223306
日期:2017.2
ABSTRACT Twenty five uridine analogues have been tested and compared with uridine with respect to their potency to bind to E. coli uridine phosphorylase. The kinetic constants of the phosphorolysis reaction of uridine derivatives modified at 2′-, 3′- and 5′-positions of the sugar moiety and 2-, 4-, 5- and 6-positions of the heterocyclic base were determined. The absence of the 2′- or 5′-hydroxyl group is
摘要已经测试了二十五个尿苷类似物,并就其与大肠杆菌尿苷磷酸化酶的结合能力与尿苷进行了比较。确定了在糖部分的2'-,3'-和5'-位以及杂环碱基的2-,4-,5-和6-位上修饰的尿苷衍生物的磷酸分解反应的动力学常数。2'-或5'-羟基的不存在对于成功的结合和磷酸分解不是至关重要的。另一方面,2'-和5'-羟基均不存在导致底物与酶结合的丧失。当不存在3'-羟基时,观察到相同的效果,从而强调了该基团的关键作用。我们的数据阐明了大肠杆菌尿苷磷酸化酶和大肠杆菌对核糖和2'-脱氧核糖核苷的识别机制。大肠杆菌胸苷磷酸化酶。在本研究中获得的动力学结果与可用的X射线结构进行比较,并对酶-底物复合物中的氢键进行分析,结果表明尿苷在尿苷磷酸化酶的活性位点采用了不同寻常的高Syn构象。