Table 3.

Specific activities of the wild-type and mutant LacA enzymes using oNPG as substrate

Transformant	Mutant LacA	Specific activity (U/mg)	Specific activity relative to wild-type (%)
WT		2.48 ± 0.06	100
259	F361Y	1.11 ± 0.075	44.42 ± 3.01
	A524T	2.53 ± 0.078	102.19 ± 3.16
461	E62V	2.39 ± 0.045	96.31 ± 1.8
	R77W	2.56 ± 0.068	103.39 ± 2.74
	A191V	2.49 ± 0.073	100.6 ± 2.95
	A301V	0.59 ± 0.014	23.69 ± 0.56

The relative activity of β-galactosidase was determined in 100 mM buffer Z (pH 7.0) at 55°Cwith substrate oNPG (4 mg/ml)