Biochemical characterization of the THIN-B metallo-beta-lactamase of Janthinobacterium lividum |
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Authors: | Docquier Jean-Denis Lopizzo Teresa Liberatori Sabrina Prenna Manuela Thaller Maria Cristina Frère Jean-Marie Rossolini Gian Maria |
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Affiliation: | Dipartimento di Biologia Molecolare, Laboratorio di Fisiologia e Biotecnologia dei Microrganismi, Università di Siena, Siena, Italy. |
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Abstract: | The THIN-B metallo-beta-lactamase, a subclass B3 enzyme produced by the environmental species Janthinobacterium lividum, was overproduced in Escherichia coli by means of a T7-based expression system. The enzyme was purified (>95%) by two ion-exchange chromatography steps and subjected to biochemical analysis. The native THIN-B enzyme is a monomeric protein of 31 kDa. It exhibits the highest catalytic efficiencies with carbapenem substrates and cephalosporins, except for cephaloridine, which acts as a poor inactivator. Individual rate constants for inactivation by chelators were measured, suggesting that inactivation occurred by a mechanism involving formation of a ternary complex. |
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