Characterization of R Factor Beta-lactamases by the Acidimetric Method
Overview
Affiliations
The properties and regulation of beta-lactamases produced by certain R factors derived from ampicillin-resistant strains of Escherichia coli and Klebsiella were characterized. beta-Lactamase activity was determined by the acidimetric method with phenol red as indicator. The sensitivity of this assay was increased by employing phosphate buffer at a final concentration of 0.4 mm; as little as 0.05 unit (1 unit equals the amount of beta-lactamase that hydrolyzes 1 mumole of benzyl penicillin per hr at pH 7.6 and 25 C) could be detected. This assay is rapid and convenient and appears to be superior to other methods currently employed to assay R factor beta-lactamases. Two classes of beta-lactamases were distinguished on the basis of substrate profile, heat inactivation, and K(m) values. The regulation of most of these R factor beta-lactamases, like certain other R factor enzymes, is subject to cyclic adenosine monophosphate-mediated catabolite repression.
Fluorescent Mesoporous Nanoparticles for β-Lactamase Screening Assays.
Tummala S, Huang W, Wu B, Chang K, Ho Y ChemistryOpen. 2020; 9(10):1074-1081.
PMID: 33117628 PMC: 7582675. DOI: 10.1002/open.202000221.
Kwon J, Bal J, Hwang H, Kim J J Microbiol. 2008; 46(4):456-61.
PMID: 18758738 DOI: 10.1007/s12275-008-0106-2.
Kontomichalou P, Papachristou E, Levis G Antimicrob Agents Chemother. 1974; 6(1):60-72.
PMID: 15828172 PMC: 429048. DOI: 10.1128/AAC.6.1.60.
Characterization of eight beta-lactamases of Gram-negative bacteria.
Sawai T, Kanno M, Tsukamoto K J Bacteriol. 1982; 152(2):567-71.
PMID: 6752115 PMC: 221503. DOI: 10.1128/jb.152.2.567-571.1982.
Macrina F, Weatherly G, Curtiss 3rd R J Bacteriol. 1974; 120(3):1387-400.
PMID: 4612021 PMC: 245926. DOI: 10.1128/jb.120.3.1387-1400.1974.