Table 1. Specific Activity of TxGH116 and Catalytic Residue Mutants with Aryl and Alkyl Glycosides and Oligosaccharides.

	specific activity (μmol mg–1 min–1)a,b
substrate	TxGH116 wild type	D593A	E441A
4NP β-d-glucoside	27.3 (100%)	0.0772 (100%)	0.000528
4NP β-d-galactoside	8.90 (33%)	-c	-c
4NP N-acetyl-β-d-glucosaminide	0.123 (0.45%)	-	-
4NP α-d-galactoside	< 0.01 (<0.04%)	-	-
4NP α-l-arabinoside	< 0.01 (<0.04%)	-	-
4NP β-d-fucoside	< 0.01 (<0.04%)	-	-
4NP α-d-glucoside	< 0.01 (<0.04%)	-	-
4NP β-d-mannoside	< 0.01 (<0.04%)	-	-
4NP β-d-xyloside	< 0.01 (<0.04%)	-	-
4NP β-cellobioside	0.302 (1.1%)	-	-
gentiobiose	2.23 (8.2%)	-	-
sophorose	4.10 (15%)	-	-
laminaribiose	11.7 (43%)	0.000245 (0.32%)	-
laminaritriose	16.1 (59%)	0.000478 (0.62%)	-
laminaritetraose	15.0 (55%)	0.000490 (0.62%)	-
laminaripentaose	16.5 (60%)	0.000524 (0.68%)	-
cellobiose	13.4 (49%)	0.000345 (0.45%)	-
cellotriose	15.6 (57%)	0.000538 (0.70%)	-
cellotetraose	14.9 (55%)	0.000498 (0.65%)	-
cellopentaose	13.8 (51%)	0.000448 (0.58%)	-
cellohexaose	13.5 (49%)	0.000422 (0.55%)	-
methyl β-d-glucoside	0.0817 (0.30%)	-	-
n-heptyl-β-d-glucoside	3.74 (14%)	-	-
n-octyl β-d-glucoside	3.58 (13%)	-	-

^aThe assay contained 1 mM substrate in 50 mM MES buffer, pH 5.5, at 60 °C.

^bPercent activity relative to glucose or 4NP released from 4NP β-d-glucopyranoside is given in parentheses. The values for disaccharide hydrolysis were determined by dividing the amount of glucose released by 2, since two glucose molecules are released per glycosidic bond hydrolyzed. For oligosaccharides, which may release more than one glucose molecule per substrate molecule due to sequential cleavage, the values quoted are for total glucose released.

^cThe dashes mean that the values were not determined for the mutant enzymes due to low activity.