C类β-内酰胺酶底物中离去基团的动力学和结构影响

Kinetic and structural consequences of the leaving group in substrates of a class C beta-lactamase.

作者信息

Ahn Yong-Mo, Pratt R F

机构信息

Department of Chemistry, Wesleyan University, Middletown, CT 06459, USA.

出版信息

Bioorg Med Chem. 2004 Mar 15;12(6):1537-42. doi: 10.1016/j.bmc.2003.12.042.

DOI:10.1016/j.bmc.2003.12.042

PMID:15018927

Abstract

The class C beta-lactamase of Enterobacter cloacae P99 is known to catalyze the hydrolysis of certain acyclic (thio)esters. Previous experiments have employed thioglycolate, m-hydroxybenzoate, and phenylphosphate leaving groups. The relative effectiveness of these leaving groups has now been quantitatively assessed by employment of a series of compounds with common acyl groups, and found to rank in the order phenylphosphate >m-hydroxybenzoate >thioglycolate. Structural models suggest that these leaving groups interact during acylation principally with Tyr 150, Lys 315, and Thr 316 of the beta-lactamase active site. The positions of the leaving group carboxylates in these models is compared with those in published crystal structures of complexes of class C beta-lactamases with beta-lactams. The particular effectiveness of the acyl phosphate indicates the positions of two oxyanions that strongly interact with the active site. This information should be useful in the design of inhibitors of class C beta-lactamases.

摘要

已知阴沟肠杆菌P99的C类β-内酰胺酶可催化某些无环（硫）酯的水解。以往的实验使用了硫代乙醇酸酯、间羟基苯甲酸酯和苯基磷酸酯离去基团。现在通过使用一系列具有常见酰基的化合物对这些离去基团的相对有效性进行了定量评估，发现其排序为苯基磷酸酯＞间羟基苯甲酸酯＞硫代乙醇酸酯。结构模型表明，这些离去基团在酰化过程中主要与β-内酰胺酶活性位点的Tyr 150、Lys 315和Thr 316相互作用。将这些模型中离去基团羧酸盐的位置与已发表的C类β-内酰胺酶与β-内酰胺复合物晶体结构中的位置进行了比较。酰基磷酸酯的特殊有效性表明了与活性位点强烈相互作用的两个氧阴离子的位置。这些信息应有助于C类β-内酰胺酶抑制剂的设计。