TABLE 2.
Specific activity of purified Xyn10A at different temperatures and pH
| Temp (°C) | Sp acta at pH: |
||||
|---|---|---|---|---|---|
| 4.0 | 5.0 | 6.0 | 7.0 | 8.0 | |
| 100 | 37 ± 17 (12%) | 206 ± 35 (65%) | 91 ± 19 (28%) | — | — |
| 90 | 41 ± 9 (13%) | 187 ± 15 (58%) | 350 ± 27 (100%) | 158 ± 7 (49%) | — |
| 80 | — | 98 ± 44 (31%) | 210 ± 4 (66%) | 169 ± 9 (53%) | — |
| 70 | — | 68 ± 5 (21%) | 111 ± 7 (35%) | 72 ± 11 (22%) | 71 ± 1 (22%) |
| 60 | — | 63 ± 14 (20%) | 67 ± 1 (21%) | 68 ± 2 (21%) | 48 ± 2 (15%) |
a
Specific activity in μmol xylose-reducing equivalents min−1 mg protein−1 ± standard deviation. n ≥ 4. Values in parentheses are percent activities relative to the maximum activity (at 90°C and pH 6.0). Dashes indicate an activity value less than 10% of maximal; activities at 30 to 50°C, as well as at pH 3.0 and pH 9.0, were less than 10% of maximal (data not shown). The pH of the assay mixture was measured at the end of each assay, and no significant change in pH was found in assays in the pH 3 to 8 range. The pH at the end of the pH 9 assays was consistently 8.6. No significant differences were seen between measurements of pH at room temperature or at 90°C.