Table 2 Analysis of the proposed sites for site-directed mutagenesis based on structural simulation
Proposed sites | Mutation information | Annotation |
|---|---|---|
T75 | A75 | T75 was located adjacent to the α-helical bundle. When the hydrophilic amino acid threonine was replaced with the hydrophobic amino acid alanine, the steric hindrance could be reduced and the substrate channel could enlarged, ultimately affect the catalytic activity of the protein |
K115 | R115, T115 | The side-chain of K115 is oriented outward. After the lysine was mutated to either arginine or threonine, the orientation could change and subsequently affect the steric hindrance |
S198 | D198, Y198 | After S198 was mutated to D198 or Y198, additional interaction may be created with other amino residue, such as A69, and consequently affect the protein’s structure |
L212 | V212, I212 | L212 was located at the bottom of the cavity formed by the α-helical bundle. The mutation of L212 to either V212 or I212 may result in enlargement of the substrate channel of the protein, consequently affect its catalytic activity |
D266 | K266, A266 | D266 is hydrogen bonded to S74. After D266 was mutated to K266 or A266, the hydrogen bond between them disappeared. This loss of the hydrogen bond may increase the flexibility and enlarge the substrate channel |