@article{mbs:/content/journal/micro/10.1099/00221287-88-1-169, author = "Matthew, Margaret and Harris, Anne M. and Marshall, Monica J. and Ross, G. W.", title = "The Use of Analytical Isoelectric Focusing for Detection and Identification of β-Lactamases", journal= "Microbiology", year = "1975", volume = "88", number = "1", pages = "169-178", doi = "https://doi.org/10.1099/00221287-88-1-169", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-88-1-169", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", abstract = "SUMMARY: β-Lactamases (EC. 3.5.2.6) from strains of Gram-negative bacteria have been studied using analytical isoelectric focusing. This permits a visual comparison of the patterns of β-lactamase bands produced by enzymes from different organisms. Purification of crude intracellular preparations is unnecessary and the technique is sufficiently sensitive to demonstrate β-lactamase in mutants previously reported to lack the enzyme. R factor RTEM and RP1 β-lactamases that have not been distinguished from one another biochemically or immunologically can be differentiated by isoelectric focusing. Conversely, the enzymes specified by the R factors RTEM, R1 and RGN14, with identical isoelectric focusing patterns, have the same biochemical properties. Chromosomal and R factor-mediated β-lactamases from single strains have been separated and their identities confirmed by immunoisoelectric focusing. R factor-mediated enzymes gave identical isoelectric focusing patterns irrespective of the host strain. Isoelectric focusing can therefore be used to observe the transfer of β-lactamases carried by R factors.", }