title: Variant of penicillinase mediated by an R factor in Escherichia coli.
abstract: The penicillinase from an Escherichia coli strain harboring an R factor R(GN823) was purified and its properties were compared with those of a known type I penicillinase mediated by R factors. The molecular weight and S(20,w) of the enzyme were 22,600 and 2.42S, respectively. The isoelectric point of the enzyme was 6.9. These values are clearly different from those of type I penicillinase. The specific activity of the enzyme was 84,700 units per mg of the purified enzyme protein, which is about 20 times higher than that of the type I penicillinase. However, similarities were observed between the enzyme and the type I-penicillinase at optimal pH (6.5 to 7.0), optimal temperature (40 to 45C), substrate specificity, Michaelis constants for penicillins and cephaloridine, and effect of inhibitors. Furthermore, antiserum against type I penicillinase showed cross-reaction against this enzyme. The enzyme was named type Ib penicillinase, and the original type I penicillinase was renamed type Ia-penicillinase.
mesh_terms: D000362:Agar; D001426:Bacterial Proteins; D002509:Cephaloridine / Q000494:pharmacology; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D003429:Cross Reactions; D004586:Electrophoresis; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000276:immunology; D005782:Gels; D014644:Genetic Variation; D005827:Genetics, Microbial; D006863:Hydrogen-Ion Concentration; D007106:Immune Sera; D007525:Isoelectric Focusing; D008747:Methylcellulose; D008970:Molecular Weight; D009995:Osmosis; D010403:Penicillin Resistance; D010405:Penicillinase / Q000302:isolation & purification / Q000378:metabolism; D010406:Penicillins / Q000494:pharmacology; D013696:Temperature; D065093:beta-Lactamase Inhibitors
chemical_list: D001426:Bacterial Proteins; D005782:Gels; D007106:Immune Sera; D010406:Penicillins; D065093:beta-Lactamase Inhibitors; D000362:Agar; D008747:Methylcellulose; D010405:Penicillinase; D002509:Cephaloridine