Solution structure of N-terminal segment of hepatitis B virus surface antigen Pre-S1

A synthetic peptide, the N-terminus of hepatitis B virus surface antigen Pre-S1, was studied by two-dimensional NMR techniques. A series of(1)H nuclear magnetic resonance experiments were used to complete the identification of spin systems and sequential assignments of this 28-residue peptide. 157 distance constraints and 55 dihedral angle constraints were obtained. 20 structures with the lowest target function were selected by the distance geometry program DIANA. Energy minimization and the following 100 ps time-averaged restrained molecular dynamics (TR-MD) simulation in aqueous solution were performed for each conformer. After TRMD simulation, three locally convergent regions corresponding to residues 22-31, 36-40, 41-46 were found. The averaged pairwise root-mean-square deviation (RMSD) of backbone atoms for them were (1.71+/-0.49)A, (0.76 +/-0.31)A, (1.05 +/- 0.52)A, respectively. Four reverse turns found in these regions, residues 22-25, 37-40, 41-44 and 43-46, correspond to several important antibody binding sites revealed in relevant immunological research.