  Beta-lactamases (Actinomycetes species); Duez, Colette  ; Frère, Jean-Marie et alin Methods in Enzymology (1975), XLIII Detailed reference viewed: 12 (0 ULg)DD-carboxypeptidase-transpeptidase and killing site of beta-lactam antibiotics in Streptomyces strains R39, R61, and K11; ; Ghuysen, Jean-Marie et alin Antimicrobial Agents and Chemotherapy (1973), 3(2), 181-187 Additional evidence is given that in Streptomyces strains R39, R61, and K11 the same enzyme performs dd-carboxypeptidase and transpeptidase activities and that this enzyme is the killing site of beta ... [more ▼] Additional evidence is given that in Streptomyces strains R39, R61, and K11 the same enzyme performs dd-carboxypeptidase and transpeptidase activities and that this enzyme is the killing site of beta-lactam antibiotics. With strain R61, it was found that the exocellular enzyme has a sensitivity towards some antibiotics different from that of the membrane-bound enzyme. Under the growth conditions used in the present investigations, beta-lactamase activity was not involved in susceptibility to beta-lactam antibiotics. [less ▲] Detailed reference viewed: 3 (0 ULg)Exocellular beta-lactamases of Streptomyces albus G and strains R39 and K11; ; et al in Antimicrobial Agents and Chemotherapy (1973), 3(2), 289-298 The beta-lactamases excreted by the highly benzylpenicillin-susceptible Streptomyces strain R39 and the highly benzylpenicillin-resistant Streptomyces albus G were isolated and purified. Neither beta ... [more ▼] The beta-lactamases excreted by the highly benzylpenicillin-susceptible Streptomyces strain R39 and the highly benzylpenicillin-resistant Streptomyces albus G were isolated and purified. Neither beta-lactamase exhibited dd-carboxypeptidase activity. Both were anionic at pH 8.3, did not require metal ions, and were not sensitive to iodine, but were inhibited by Cu(2+) and readily inactivated by heat. p-Chloromercuribenzoate, iodoacetate, p-aminobenzoate, and substrates and inhibitors of dd-carboxypeptidase had no effect on beta-lactamase activity. The K(m) and V(max) values for beta-lactamase activity were studied with 6-aminopenicillanic acid and with various penicillins and cephalosporins. The beta-lactamase from the related strain K11 of Streptomyces, which is intermediate in its susceptibility to benzylpenicillin, was partially purified, and its activity was compared on the various substrates. [less ▲] Detailed reference viewed: 4 (0 ULg)Penicillin-sensitive DD-carboxypeptidases from Streptomyces strains R39 and K11; ; Frère, Jean-Marie et alin Biochemistry (1972), 11(7), 1290-1298 Detailed reference viewed: 5 (0 ULg) |
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