TABLE 2.

Kinetic parameters (kcat and Km) and physiologic efficiency (kcat/Km) of CTX-M-14 enzyme against various β-lactam antibiotics

Antibiotickcat (s−1)Km (μM)kcat/KmRelative kcat/Km
Penicillin G1,200 ± 6052 ± 4.322.9100
Cephalothin6,900 ± 32098 ± 8.070.5308
Cephaloridine6,500 ± 430168 ± 4.038.7169
Cefotaxime1,100 ± 4054 ± 3.220.387
Ceftazidime<0.01440 ± 26<0.01<0.04
Aztreonam<0.010.48 ± 0.06<0.02<0.04
Nitrocefin150 ± 1.91.12 ± 0.02133581