TABLE 3.

Kinetic parameters of TEM-60 mutants with β-lactamase inhibitors^a

Enzyme	β-IP k+2/K (M−1 s−1)	Tazobactam
		K (μM)	k+2/K (M−1 s−1)
TEM-1	2.8 × 105	0.014	5.5 × 102
TEM-60	2.6 × 105	0.020	2.1 × 104
TEM-60 P51L	NIb	0.60	NDc
TEM-60 K104E	1.7 × 104	113	ND
TEM-60 S164R	8.9 × 102	0.03	ND

^aKnown parameters for TEM-60 (3) and for TEM-1 (2, 13) are also shown for comparison. Values are the means of three measurements. The standard deviation was always lower than 5%.

^bNI, no inhibition was detected using a substrate concentration up to 2 mM.

^cND, not determined.