Table 3.

Kinetics parameters.

Antibiotics	SHV-104			SHV-1
	k cat	Km	k cat/Km	k cat	Km	k cat/Km
	(sec−1)	(μM)	(μM−1 sec−1)	(sec−1)	(μM)	(μM−1 sec−1)
Benzylpenicillin	55	94	0.6	360	20	18
Ticarcillin	80	10	8	80	27	3
Nitrocefin	830	43	19	290a	21a	14a
Cephalothin	30	68	0.44	9	30	0.3
Cefuroxime	0.53	540	0.001	0.5	100	0.005
Cefotaxime	>1.8	>600	0.003	N.D.	N.D.	N.D.

ND: not determinable because the hydrolysis rate was too low.

^aThe kinetic constants of nitrocefin for SHV-1 are from Thomson et al. [10].