TABLE 5.

Main kinetic similarities and differences among the three variants of AmpC from M. morganii

Antibiotic	AmpC enzyme	kcat (s−1)	Km (μM)	kcat/Km (μM−1 · s−1)
Ampicillin	M19	0.06 ± 0.003	0.08 ± 0.004	0.75 ± 0.04
	M29	0.06 ± 0.003	0.13 ± 0.009	0.5 ± 0.02
	M37	0.06 ± 0.003	0.06 ± 0.006	1 ± 0.05
Imipenem	M19	0.11 ± 0.006	4 ± 0.1	0.027 ± 0.002
	M29	0.07 ± 0.003	2 ± 0.3	0.035 ± 0.002
	M37	0.07 ± 0.004	1 ± 0.06	0.07 ± 0.004
Cephalothin	M19	14 ± 2	46 ± 13	0.3 ± 0.04
	M29	140 ± 35	148 ± 10	1 ± 0.2
	M37	6 ± 0.8	106 ± 10	0.06 ± 0.007
Cefotaxime	M19	≤0.07 ± 0.004	0.5 ± 0.06	0.14 ± 0.008
	M29	0.032 ± 0.002	0.02 ± 0.0016	1.6 ± 0.1
	M37	≤0.09 ± 0.003	0.09 ± 0.01	1 ± 0.03