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Zawadzke Laura E.; Smith Tom J.; Herzberg Osnat 《Protein engineering, design & selection : PEDS》1995,8(12):1275-1285
The ß-lactamase from Staphylococcus aureus PCI hasbeen cloned into an Escherichia coli vector for site-directedmutagenesis and high-level protein expression. A mutant enzymehas been produced in which Ala238 is replaced by a serine, andIle239 is deleted (A238S:I239del). The engineered enzyme hydrolysesthird-generation cephalosporins substantially more rapidly thanthe parental enzyme does, while hydrolysis of benzylpenicillinis slower with the mutant than with the wild-type and nativeenzymes. The mutant P-lactamase has been crystallized and thestructure determined and refined at 2.8 A resolution. The dispositionof the ß-strand which forms the side of the activesite is altered in comparison with the native S.aureus ß-lactamasestructure, widening the active site cleft and providing spaceto accommodate the bulky side-chains of the third-generationcephalosporins. 相似文献
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