Table 3. Structural factors potentially involved in the weak thermal stability of the psychrophilic cellulase CelG.
| Parameters | Cel5 | CelG | Expected effect |
|---|---|---|---|
| Catalytic domain | |||
| Proline content | 10 | 7 | Loop mobility increase |
| Glycine content | 22 | 28 | Backbone mobility increase |
| Arginine content | 10 | 6 | Weak electrostatic interactions decrease |
| Salt bridges | 13 | 9 | Ionic interactions decrease |
| Arginine+lysine | 30 | 18 | Imbalance of surface charges |
| Solvent-accessible non-polar residues | 19 | 14 | Decreases hydrophobic effect on folding |
| Hydrophobic clusters | 3(+2)* | 5 | Decreases hydrophobic effect on folding |
| Cavities | 5 | 8 | Folding compactness decrease |
| Volume of cavities (Å3) | 21 | 52 | Folding compactness decrease |
| CBM | |||
| Salt bridges | 13 | 9 | Ionic interactions decrease |
| Hydrophobic clusters | 1 | 0 | Decreases hydrophobic effect on folding |
| Hydrophobic core | (1)* | 1 | Decreases hydrophobic effect on folding |
| Cavities | 0 | 1 | Folding compactness decrease |
* Weaker hydrophobicity resulting from substitution for polar side chain(s).