Table 2.

The Substrate Specificity of the Wild-Type and Mutant Enzymes

Substrate		Artificial substrate (2 mM)			Natural substrate (2 mM)
		pNPGlc	pNPGal	pNPFuc	Cellubiose	Gentiobiose	Lactose
Linkage of glycosyl group		β-Glucose	β-Galactose	β-Fucose	β(1,4)-Glucose	β(1,6)-Glucose	β(1,4)-Galactose
Specific activity (U/mg)	TmBglA	731.1 ± 6.82	304.8 ± 9.83	528.4 ± 7.45	26.6 ± 1.09	15.7 ± 0.15	6.8 ± 0.31
	N222F	846.3 ± 8.91	520.7 ± 8.45	954.3 ± 11.78	9.5 ± 0.26	33.4 ± 1.57	0.9 ± 0.08
	N223C	899.7 ± 9.34	331.0 ± 8.37	826.2 ± 9.49	24.7 ± 1.78	9.1 ± 0.16	3.9 ± 0.32
	N223Q	881.4 ± 6.57	266.3 ± 6.59	844.0 ± 9.31	23.5 ± 0.74	9.7 ± 0.31	5.3 ± 0.05
	G224A	750.7 ± 9.93	317.3 ± 3.77	559.7 ± 6.25	42.0 ± 1.78	12.1 ± 0.20	8.9 ± 0.13
	Y295F	4.7 ± 0.16	4.3 ± 0.22	5.1 ± 0.27	0.4 ± 0.01	0.2 ± 0.01	0.1 ± 0.01
	F414S	3.4 ± 0.14	1.3 ± 0.10	5.3 ± 0.26	0.1 ± 0.01	0.3 ± 0.01	0.1 ± 0.01
Relative activity (%)	TmBglA	100	41.7 ± 2.28	72.3 ± 3.64	3.6 ± 0.18	2.1 ± 0.04	0.9 ± 0.03
	N222F	100	61.5 ± 2.32	112.8 ± 7.90	1.1 ± 0.01	3.9 ± 0.12	0.1 ± 0.00
	N223C	100	36.8 ± 1.55	91.8 ± 2.47	2.7 ± 0.09	1.0 ± 0.03	0.4 ± 0.00
	N223Q	100	30.2 ± 2.30	95.8 ± 5.17	2.7 ± 0.07	1.1 ± 0.00	0.6 ± 0.02
	G224A	100	42.3 ± 3.10	74.6 ± 4.78	5.6 ± 0.24	1.6 ± 0.08	1.2 ± 0.05
	Y295F	100	91.3 ± 5.34	108.4 ± 8.71	8.5 ± 0.29	4.2 ± 0.18	2.1 ± 0.09
	F414S	100	38.0 ± 0.69	158.8 ± 7.18	2.9 ± 0.08	8.8 ± 0.32	2.9 ± 0.10

Note. Values represent the means ± standard deviation; n = 3 (P < 0.05).