TABLE 3.

Enzyme kinetics

Enzyme class	Source	Km (μM)								Reference(s)
		Benzylpenicillin	Ampicillin	Cefazolin	Cephaloridine	Cefoxitin	Cefotaxime	Aztreonam	Imipenemb
C	E. cloacae	0.6	0.4	1,500	70	0.024	0.01	0.0012	0.04	99, 100
	C. freundii	0.4	0.2	600	35	0.250	0.005	0.0014	0.085	99, 100
	E. coli K-12	4.4	3.5	400	170	0.650	1.7	0.0012	0.8	99, 100
	S. marcescens	1.7	0.01	540	275	0.3	12	0.058	0.06	99, 100, 148
	P. aeruginosa	1.7	0.5	—a	20	0.05	0.2	0.050	0.026	99, 100
	ACT-1	2.1	1.7	430	>200	0.5	0.07	0.012	0.37	25
	MIR-1	0.4	0.16	—a	93	0.75	4	0.004	0.15	25
	CMY-1	1	2.2	54	110	0.055	0.015	0.01	0.05	25
	CMY-2	0.4	0.16	—a	93	0.07	0.0012	<0.003	ND	25
A	TEM-2	15-20	22	680	2,100		3,000			204
	B. licheniformis	76	143	12	135		205			204
D	OXA-29	10	16	30			128	210	NH	96

^aBiphasic kinetics.

^bND, not determined; NH, no hydrolysis detected.