铜绿假单胞菌Dalgleish菌株组成型β-内酰胺酶的纯化及特性

Purification and properties of a constitutive beta-lactamase from Pseudomonas aeruginosa strain Dalgleish.

Furth A J

Biochim Biophys Acta. 1975 Feb 19;377(2):431-43. doi: 10.1016/0005-2744(75)90323-x.

Abstract

The beta-lactamase (penicillin amido-beta-lactamhydrolase EC 3.5.2.6) appeared to be periplasmic rather than truly intracellular, since it was released by freeze-thawing without gross morphological changes in the cell. 2. The partially purified enzyme had pI between 5.0 and 5.5, mol. wt 32 000 and a broad pH vs activity profile with a maximum at pH 8. 3. The cephalosporins tested were hydrolysed less rapidly than most of the penicillins, and the Km values for penicillins were lower than for cephalosporins. However cloxacillin was hydrolysed very slowly although it was strongly bound. The substrate-induced inactivation common to many beta-lactamases was particularly marked with cephaloridine and cloxacillinmthe cloxacillin-induced inactivation was shown to be reversible.

摘要

β-内酰胺酶（青霉素酰胺-β-内酰胺水解酶，EC 3.5.2.6）似乎位于周质空间而非真正存在于细胞内，因为通过冻融法可将其释放出来，且细胞没有明显的形态变化。2. 部分纯化的酶的等电点在5.0至5.5之间，分子量为32000，pH与活性关系曲线较宽，在pH 8时活性最高。3. 所测试的头孢菌素的水解速度比大多数青霉素慢，青霉素的米氏常数低于头孢菌素。然而，氯唑西林虽然结合紧密，但水解速度非常慢。许多β-内酰胺酶常见的底物诱导失活现象在头孢菌素和氯唑西林中尤为明显，氯唑西林诱导的失活被证明是可逆的。