Table 1.

β-Lactamase activity in the crude extract of clone 8AI (DH5α[pLLB-8AI]) with nitrocefin (NCF), imipenem (IMI), and meropenem (MEM)a

StrainSp act (pmol/min/μg of protein)
NCFIMIMEM
DH5α(pLLB-8AI)386 ± 2027 ± 2132 ± 7
DH5α(pACYC184)<10<5<5
  • a The basal activity of E. coli DH5α carrying an empty vector is also shown for comparison. Crude extracts were prepared from cells collected in the late-exponential phase of growth (A 600, 1.5 to 1.8). Specific activities are the mean values of three measurements ± standard deviations.