TABLE 3.

Substrate specificity of CelA^a

Substrates	Km (mM)	Sp actb	% Relative activity
β-Glucosides
Cellobiose	0.05	386.0	100
Gentiobiose	0.26	82.9	21
Salicin	0.24	38.8	10
PNPG	1.33	138.0	35
Cellobiosides
Cellobiose		449.2	100
Cellotriose		171.7	38
Cellotetraose		168.0	37
Cellopentaose		153.4	34

^aTwo classes of substrates, β-glucosides and cellobiosides, were used; in each set of experiments, cellobiose was used as a reference. Because of differences in experimental procedures, the absolute specific activities between the two experiments cannot be compared. 

^bMicromoles of glucose or p-nitrophenol produced per minute per milligram of protein.