Letarte R, Devaud-Felix M, Pechere J C, Allard-Leprohon D
Antimicrob Agents Chemother. 1977 Aug;12(2):201-5. doi: 10.1128/AAC.12.2.201.
A hospital strain of Enterobacter aerogenes (MULB 250) isolated from a urinary tract infection was found to be cephalosporin and ampicillin resistant and carbenicillin susceptible. The beta-lactamase produced by this strain was extracted and purified by means of affinity chromatography, using a cephalosporin C-bound Sepharose 4B column. The purified enzyme was tested for hydrolysis of penicillin and various cephalosporins. The K(m) value is 11.8 muM for benzyl penicillin and 130 muM for cephalosporin C. The isoelectric point of the enzyme is 9.3, and its molecular weight is 29,500 +/- 1,000. Rabbit antiserum obtained against this MULB 250 beta-lactamase showed no cross-reaction with other penicillinases or cephalosporinases in neutralization tests. Comparisons of results obtained with other beta-lactamases, particularly from Enterobacter cloacae P99, indicate that the Enterobacter MULB 250 enzyme presents a typical cephalosporinase profile. As far as we know, this type of enzyme is relatively rare.
从尿路感染中分离出的一株产气肠杆菌医院菌株（MULB 250）被发现对头孢菌素和氨苄西林耐药，但对羧苄西林敏感。该菌株产生的β-内酰胺酶通过亲和色谱法进行提取和纯化，使用结合头孢菌素C的琼脂糖凝胶4B柱。对纯化后的酶进行了青霉素和各种头孢菌素水解测试。该酶对苄青霉素的K(m)值为11.8 μM，对头孢菌素C的K(m)值为130 μM。该酶的等电点为9.3，分子量为29,500 ± 1,000。针对这种MULB 250β-内酰胺酶获得的兔抗血清在中和试验中与其他青霉素酶或头孢菌素酶无交叉反应。与其他β-内酰胺酶（特别是阴沟肠杆菌P99的β-内酰胺酶）的结果比较表明，产气肠杆菌MULB 250酶呈现出典型的头孢菌素酶谱。据我们所知，这种类型的酶相对罕见。
