Table 3.

Comparative kinetic parameters of β-lactamase TEM-2 and its mutants

DrugKinetic parameters ofa:
TEM-2TEM-18TEM-56TEM-3TEM-21
kcat Km kcat/Km kcat Km kcat/Km kcat Km kcat/Km kcat Km kcat/Km kcat Km kcat/Km
Benzylpenicillin1,50018831,40024581,40022634567.55095.5
Amoxicillin1,20020601,3004131.71,33040333156.243202.15
Ticarcillin1951216.2280647300743924.5732.3
Piperacillin1,2754031.81,36040341,35038357212646123.8
Cephalothin3003500.862251351.72501401.848232.118550.33
Cephaloridine8258001.01,3601,2001.11,3501,2001.143301.41201201.0
Cefoperazone7002303.05501703.25501803.028201.419300.63
Cefuroxime31,000<0.01104800.0284700.0228900.3118850.21
Ceftriaxone<1ND<0.01218000.03168400.0281801532100.25
Cefotaxime1.5ND<0.01351,6600.02281,7000.0220210021204000.3
Ceftazidime<1ND<0.01<1ND<0.01<1ND<0.01182000.14ND<0.01
  • a kcat values are given in per second units, Km values are given in micromolar units, and kcat/Km values are given in per micromole per second units. The values given forkcat and Km were computed on the basis of at least three independent experiments. ND, not detected (high Km or Ki values).