Mechanism of Inhibition of the Class C β-Lactamase of <i>Enterobacter </i><i>c</i><i>loacae</i> P99 by Cyclic Acyl Phosph(on)ates: Rescue by Return
作者:Kamaljit Kaur、Martin J. K. Lan、R. F. Pratt
DOI:10.1021/ja011094v
日期:2001.10.31
As previously described (Pratt, R. F.; Hammar, N. J. J. Am. Chem. Soc. 1998, 120, 3004.), 1-hydroxy-4,5-benzo-2,6-dioxaphosphorinone(3)-1-oxide (salicyloyl cyclic phosphate) inactivates the class C beta-lactamase of Enterobacter cloacae P99 in a covalent fashion. The inactivated enzyme slowly reverts to the active form. This paper shows that reactivation involves a recyclization reaction that regenerates
如前所述 (Pratt, RF; Hammar, NJJ Am. Chem. Soc. 1998, 120, 3004.),1-羟基-4,5-苯并-2,6-二氧杂磷啉酮(3)-1-氧化物(水杨酰基环磷酸盐)以共价方式灭活阴沟肠杆菌 P99 的 C 类β-内酰胺酶。失活的酶慢慢恢复为活性形式。本文表明,再活化涉及再生水杨酰环状磷酸酯的再循环反应,而不是共价中间体的水解。因此,失活是活性位点的缓慢可逆共价修饰。抑制剂与失活酶的热力学解离常数为 0.16 microM。用碱处理灭活的酶不会产生水杨酸,但在随后的酸水解后会产生一摩尔当量的赖氨酸丙氨酸。该结果证明水杨酰环状磷酸酯通过活性位点丝氨酸残基的(缓慢可逆的)磷酸化使酶失活。该结果与无环酰基磷酸酯的行为形成鲜明对比,后者通过酰化作用使 P99 β-内酰胺酶暂时失活(Li, N.;Pratt, RFJ Am. Chem. Soc. 1998, 120