Table 1.

MIC and enzyme specific activity measurements for TEM β-lactamase variants

Enzyme	MIC XL1-Blue*	Specific activity XL1-Blue†	Relative activity XL1-Blue, %	Specific activity SB646†	Relative activity SB646, %
TEM-1	3,000	45.9	100	16.6	100
L76N	100	0.9	2.0	1.3	7.8
L76N:M182T	2,000	19.1	41.6	7.9	47.6
L76S	250	2.2	4.8	4.8	28.9
L76S:M182T	1,500	30.0	65.4	10.2	61.4
M182T	2,000	32.3	70.4	8.0	48.2
M69I	750	7.3	15.9	1.5	9.0
M69I:M182T	750	8.8	19.2	1.4	8.4
I47Y:E48C	500	4.9	10.7	2.6	15.7
I47Y:E48C:M182T	750	11.0	24.0	3.3	19.9

^*MIC measured in μg/ml of ampicillin. 

^†Specific activity is recorded as mM ampicillin hydrolyzed per mg of protein per min at 37°C.