Figure 2.

Rates of hydrolysis of nitrocefin and ceftazidime from Escherichia coli cell lysates. Escherichia coli lysates containing Guiana extended spectrum β-lactamase (GES)-19, GES-26, and GES-19/GES-26 were prepared from cultures grown in the presence of 0.5 mM isopropyl β-d-1-thiogalactopyranoside for 20 hours to induce protein expression. (A) Hydrolysis of 50 µM nitrocefin in 50 mM HEPES pH7.4 monitored by absorbance at 482 nm. Cell lysate with both enzymes was more efficient than that of GES-19 or GES-26 individually by 4-fold and 7-fold, respectively. (B) Hydrolysis of 50 µM ceftazidime in 50 mM HEPES pH7.4 monitored by absorbance at 260 nm. Hydrolysis of ceftazidime in the presence of cell lysate containing both enzymes was 1.7-fold higher than GES-19 alone.