TABLE 4.
The binding of mutants of vCBM60 to carbohydrate ligands
Binding to the various polysaccharides was determined by ITC in 50 mm Na Hepes, pH 7.5, containing 5 mm CaCl2. The errors are presented for typical titrations.
| vCBM60 derivative | Ligand | Ka |
|---|---|---|
| m−1 | ||
| Wild type | Oat-spelt xylan | 7.2 (±0.8) × 103 |
| Wild type | Potato pectic galactan | 1.2 (±0.06) × 104 |
| Wild type | Barley β-glucan | 8.7 (±0.9) × 103 |
| W98A | Oat-spelt xylan | 5.3 (±0.9) × 103 |
| W98A | Potato pectic galactan | 6.6 (±1.0) × 103 |
| W98A | Barley β-glucan | 5.7 (±1.0) × 103 |
| H100A | Oat-spelt xylan | 8.9 (±1.1) × 102 |
| H100A | Potato pectic galactan | 2.9 (±0.2) × 104 |
| H100A | Barley β-glucan | 3.2 (±0.3) × 103 |
| vCBM60-vCBM60 | Oat-spelt xylan | 1.6 (±0.5) × 105 |
| vCBM60-vCBM60 | Potato pectic galactan | 5.0 (±1.2) × 105 |
| D55A, D60A or W85A | Oat-spelt xylan, potato pectic galactan, or barley β-glucan | No binding of each mutant to the three polysaccharides was detected |