TABLE 1.
Properties of the mutation sites
| Position | Structural context | Fractional surface accessibility* | Number of H-bonds | Histidines and charged amino acids within a radius of 10 Å within the selected positions† |
|---|---|---|---|---|
| H10 | Turn | 1.05 | 1 | His3, His4, His15, His17 |
| ⊕ Lys9, Lys18 | ||||
| ⊖ Glu14 and Asp19 | ||||
| T37 | Turn | 0.74 | 1 | His36 |
| ⊕ Lys39, Lys252, Lys257, and Arg254 | ||||
| ⊖ Asp32, Asp34, Asp110 | ||||
| S43 | Turn | 0.77 | 1 | ⊕ Lys39, Lys45, Lys257, Lys261 |
| ⊖ Asp41, Asp85 | ||||
| V135 | Turn | 0.19 | 1 | ⊕ Lys127, Lys133, and Arg27 |
| ⊖ Asp139 and Glu205 | ||||
| S152 | Random coil | 0.94 | 0 | ⊕ Lys149, Lys154 |
| ⊖ Glu221 | ||||
| T177 | End of β-sheet | 1.35 | 1 | ⊕ Lys159 and Arg58 |
| ⊖ Asp71, Asp175, Asp180, and Glu69 | ||||
| L240 | Loop | 0.58 | 1 | ⊕ Lys168, Lys170, Lys225, Lys228, and Arg227 |
| ⊖ Glu236, Glu238, Glu239, and Asp243 |
*
Fractional accessibility was determined for the wild-type amino acid as the ratio of the absolute area of each amino acid divided by the area of the same, exposed amino acid situated in a tripeptide, Ala-Xaa-Ala (Lee and Richards, 1971).
†
In addition to these charged amino acids there are charged amino acids in the region between positions 10 and 37 (Lys24, Glu26, Arg27, and Arg254).