Fig 6. β-lactamase activity assay of E. cloacae using 400 μg of pep1, pep2 and pep3 peptides.

(A) The assay was performed in 96-well plate in a 100 μl total reaction volume containing assay buffer, E. cloacae β-lactamase and nitrocefin in absence or presence of peptides pep1, pep2 and pep3. The reactions were followed by measuring absorbance at 490 nm for 10 minutes with 1-minute interval. The results represent the means of three independent experiments. Error bars represent the standard deviations from the means. (B) Brown color in wells with no peptide, 400 μg of pep1 and 400 μg of pep2 is due to hydrolyzed nitrocefin which rapidly changes color from yellow to brown when degraded due to hydrolysis. Statistical analysis was performed using two-tailed paired Student’s t-test (*, p < 0.5; **, p < 0.05; ***, p ≤ 0.005 vs. no peptide control).