Figure 3 | Scientific Reports

Figure 3

From: Proteomic identification of Axc, a novel beta-lactamase with carbapenemase activity in a meropenem-resistant clinical isolate of Achromobacter xylosoxidans

Figure 3

Axc has carbapenemase activity. (A) Axc was expressed in E. coli and cell extracts were tested for the ability to hydrolyse imipenem. Bars show the A431/A560 ratio, which is a measure for the shift in pH due to imipenem hydrolysis. (B) NMR-based identification of imipenem hydrolysis by Axc. The structure of imipenem is shown, with the proton numbering used in the spectrum. The line color indicates the incubation time (red, 10 min at room temperature or black, 10 hrs at 6 °C). Imipenem hydrolysis is accompanied by the loss of the H-6 multiplet at 3.4 ppm, and a shift in the H-9 doublet, resulting in a decrease of the doublet at 1.3 ppm. Strains used (see also Table 1): KPC (JC113): Carbapenem resistant Klebsiella pneumoniae. E. coli Axc (JC107): E. coli strain C43(DE3), containing plasmid pET21-Axc; E. coli_control (JC108): E. coli strain C43, containing plasmid pET21-PPEP-1 (Pro-Pro endopeptidase 1). IPTG: isopropyl β-D-1-thiogalactopyranoside.

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