Table 3.

β-Lactamase activities and clavulanate and tazobactam IC50s for TEM-1 β-lactamase and TEM mutant enzymes

Amino acid change from TEM-1aDesignationβ-Lactamase activitybIC50 (μM)
ClavulanateTazobactam
TEM-1TEM-15,3300.080.03
M69LTEM-3358620.5
M69L, N276DTEM-351,190120.6
R244CTEM-31514101.7
G238STEM-192,9500.0010.002
G238S, M69L8530.030.02
G238S, M69L, N276D2,3600.380.04
G238S, R244C4851.50.3
G238S, E104KTEM-15290.0020.004
G238S, E104K, M69L3190.070.01
G238S, E104K, M69L, N276DTEM-509520.30.02
G238S, E104K, R244C6961.11.2
R164STEM-12250.020.02
R164S, M69L490.250.2
R164S, M69L, N276D1,4401.80.3
R164S, R244C9374.55
R164S, E104KTEM-26523<0.010.06
R164S, E104K, M69L2110.080.3
R164S, E104K, M69L, N276D4580.350.2
R164S, E104K, R244C543.52
  • a See footnote a to Table 2for a key to the amino acid substitutions.

  • b Activities are expressed as nanomoles of nitrocefin hydrolyzed per minute per milligram of protein.