TABLE 1.
Effects of metal ions and EDTA on xylanase activitya
| Ion or EDTA (mM) | Relative activity (%) |
|---|---|
| None | 100 |
| EDTA (1) | 42.2 |
| EDTA (10) | 22.2 |
| EDTA (50) | 0 |
| CaCl2 | 130.7 |
| CuCl2 | 51.2 |
| CoCl2 | 54.4 |
| FeCl2 | 261.6 |
| MgCl2 | 172.0 |
| MnCl2 | 16.5 |
| NiCl2 | 60.7 |
| ZnCl2 | 46.1 |
| CaSO4 | 191.6 |
| CuSO4 | 33.3 |
| CoSO4 | 76.3 |
| FeSO4 | 289.0 |
| MgSO4 | 174.0 |
| MnSO4 | 12.0 |
a
For the case of metal ions, the enzyme solution was mixed with the final concentration of 50 mM EDTA and dialyzed with Tris-HCl buffer (pH 7.0). Then the EDTA-treated enzyme solutions were preincubated in a mixture containing various chemicals (1 mM) at 30°C for 1 h, after which the reactivated activity was measured under the standard assay conditions.