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Beta-Lactamase I From Bacillus Cereus. Structure and Site-Directed Mutagenesis

Beta-Lactamase I From Bacillus Cereus. Structure and Site-Directed Mutagenesis

P J Madgwick, S G Waley

Biochem J. 1987 Dec 15;248(3):657-62.

PMID: 3124817

Abstract:

The sequence of the gene for beta-lactamase I from Bacillus cereus 569/H has been redetermined. Oligonucleotide-directed mutagenesis has been carried out, and the effects of the changes on the ampicillin-resistance of Escherichia coli TG1 expressing the mutant genes have been studied. Lysine-73, close to the active-site serine-70 and a highly-conserved residue, has been converted into arginine. This change had a large effect on activity, but did not abolish it. An even larger effect was found in the mutant in which glutamate-166 had been converted into glutamine; this had little or no activity. On the other hand, the conversion of glutamate-168 into aspartate gave fully active enzyme. Glutamate-166 is an invariant residue, but glutamate-168 is not. Alanine-123 has been replaced by cysteine, to give active enzyme; this change forms part of the plan to introduce a disulphide bond into the enzyme.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP9073603	Penicillinase from Bacillus cereus		9073-60-3	Price

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