Table 2. Affinities and thermodynamic properties of CBM–carbohydrate interactions as determined by ITC.
Ligand | Protein | KA (M−1) | ΔH (kcal/mol) | TΔS (kcal/mol) | n* |
---|---|---|---|---|---|
Xylopentaose | CBM4-2 | 5.13×106 | −19.08±0.06 | −9.92 | 0.95±0.002 |
X2 | 4.80×104 | −12.65±0.89 | −6.26 | 1.08±0.050 | |
Birchwood xylan | CBM4-2 | 1.71×105 | −15.21±0.29 | −8.07 | 1.06±0.015 |
X2 | 8.39×104 | −14.94±1.19 | −8.22 | 1.09±0.066 | |
Oat-spelt xylan | CBM4-2 | 6.67×105 | −17.18±0.39 | −9.23 | 1.07±0.002 |
X2 | 1.15×105 | −10.53±1.01 | −3.62 | 0.91±0.060 | |
Wheat arabinoxylan | CBM4-2 | 1.92×105 | −15.69±0.40 | −8.46 | 1.00±0.019 |
X2 | 2.19×104 | −18.95±0.71 | −13.02 | 1.01±0.025 | |
β-Glucan | CBM4-2 | 5.63×104 | −12.69±0.40 | −6.20 | 1.03±0.025 |
X2 | Weak† | ||||
Glucomannan | CBM4-2 | 1.65×103 | −16.75±32.4 | −12.34 | 1.02±1.700 |
X2 | NB‡ | ||||
Galactomannan | CBM4-2 | NB | |||
X2 | NB | ||||
Lichenan | CBM4-2 | Weak | |||
X2 | NB | ||||
Laminarin | CBM4-2 | 7.82×103 | −27.14±9.04 | −21.82 | 0.995±0.260 |
X2 | NB | ||||
Xyloglucan | CBM4-2 | Weak | |||
X-2 | NB |
* n is the number of binding sites on the protein.
† Extremely weak binding was detected but too low to quantify.
‡ NB, no binding.