MICROHETEROGENEITY OF R-PLASMID CODED BETA-LACTAMASES IN ANALYTICAL ISOELECTRIC-FOCUSING

  • 1 January 1977
    • journal article
    • research article
    • Vol. B128  (3) , 309-+
Abstract
Analytical isoelectric focusing of plasmid-coded .beta.-lactamases in polyacrylamide gels gives rise to several satellite bands besides 1 major active band (microheterogeneity). When the R plasmids are transferred by conjugation into 4 different bacterial species (Escherichia coli, Klebsiella pneumoniae, Salmonella typhimurium, Proteus mirabilis) the position of the main band remains constant, but the number and position of the satellite bands are changed. The minimal inhibitory concentrations of several .beta.-lactamines are also changed when the plasmids are transferred between these different host strains. The bacterial host might modify the physical structure and the activity of plasmid-determined .beta.-lactamases. The identification of .beta.-lactamases and comparison of their isoelectric focusing patterns should always be carried out using the same bacterial host strain.

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