TABLE 2.
Substrate | Sp act (U/mg)
|
|
---|---|---|
CDH I | CDH II | |
Cellobiose | 4.1 ± 0.5 | 15 ± 0.4 |
Lactose | 1.2 ± 0.2 | 13 ± 0.3 |
Mannitol | 0.3 ± 0.01 | 0.1 ± 0.02 |
Sorbose | 0.3 ± 0.01 | 0.1 ± 0.01 |
Each reaction mixture (total volume, 1,000 μl) contained 50 mM sodium acetate (pH 4.5), 500 μM DCPIP, a water-soluble sugar substrate at a concentration of 2 mM, and 50 mg of a cellulose preparation. The assay mixtures were incubated at 25°C for 15 min. The results are means ± standard deviations based on triplicate measurements. No activity (DCPIP reduction after 12 h of incubation) was detected when any of the following compounds was the putative electron-donating substrate: bacterial cellulose, Whatman CF 11 cellulose, Avicel cellulose, d-glucose, d-xylose, and d-mannose.