Homology modeling of three-dimension structure of hepatitis B surface antigen fragment and its ligand design

By means of the homology modeling and docking methods, a theoretical study on hepatitis B surface antigen (HBsAg) fragment (44 -170) was performed. The three-dimension structure of HBsAg fragment (44-170) is built up based on the crystal structures of whey acidic protein (PDB code 1CJH) and ricin glycosidase (PDB code 2AAI). A new ligand is designed based on the structure of acceptor HBsAg (44-170) and the ligand is docking to HBsAg fragment. The result shows that Trpl63 and Trpl65 in the complex have strong van der Waals contacts with the ligand, and this result is in agreement with the experimental one in reference reported by Wang et al. The hydrogen bonding interactions between ligand and tryptophan residues as well as proline residue of HBsAg also play an important role in locating effects. The results obtained may be helpful for further studies of the structure-based ligand designing of new compounds.