Hedberg M, Edlund C, Lindqvist L, Rylander M, Nord C E
Department of Microbiology, Huddinge University Hospital, Sweden.
J Antimicrob Chemother. 1992 Feb;29(2):105-13. doi: 10.1093/jac/29.2.105.
An imipenem resistant beta-lactamase producing strain of Bacteroides fragilis was isolated from a clinical specimen. The specific activity of the unpurified beta-lactamase was 5.5 U/mg protein. The beta-lactamase was purified 60-fold by Q Sepharose, Sephacryl S-300 and Mono Q column passages. The strain was able to inactivate imipenem and cefoxitin in broth cultures. The enzyme hydrolysed imipenem more rapidly than ampicillin, benzylpenicillin, cephalothin and cefoxitin. The activity of the enzyme was Zn2+ dependent and was completely inhibited by EDTA. The inhibition was reversed by ZnSO4. Preincubation with the common beta-lactamase inhibitors clavulanic acid, sulbactam and tazobactam did not reduce the enzyme activity. The molecular weight was determined by sodium dodecyl sulfate gradient gel electrophoresis to be 31,000 Daltons and the isoelectric point was 4.5.
从一份临床标本中分离出一株产耐亚胺培南β-内酰胺酶的脆弱拟杆菌菌株。未纯化的β-内酰胺酶的比活性为5.5 U/mg蛋白质。通过Q Sepharose、Sephacryl S-300和Mono Q柱层析，β-内酰胺酶被纯化了60倍。该菌株能够在肉汤培养物中使亚胺培南和头孢西丁失活。该酶水解亚胺培南的速度比氨苄西林、苄青霉素、头孢噻吩和头孢西丁更快。该酶的活性依赖于Zn2+，并被EDTA完全抑制。ZnSO4可逆转这种抑制作用。与常见的β-内酰胺酶抑制剂克拉维酸、舒巴坦和他唑巴坦预孵育不会降低酶活性。通过十二烷基硫酸钠梯度凝胶电泳测定分子量为31,000道尔顿，等电点为4.5。
