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 antig en Pre-S1, was studied by two-dimensional NMR techniques. A series of H-1 nuclear magnetic resonance experiments were used to complete the i dentification of spin systems and sequential assignments of this 28-re sidue peptide. 157 distance constraints and 55 dihedral angle constrai nts were obtained. 20 structures with the lowest target function were selected by the distance geometry program DIANA. Energy minimization a nd the following 100 ps time-averaged restrained molecular dynamics (T RMD) 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 roo t-mean-square deviation (RMSD) of backbone atoms for them were (1.71 /- 0.49) Angstrom, (0.76 +/- 0.31) Angstrom, (1.05 +/- 0.52) Angstrom, respectively. Four reverse turns found in these regions, residues 22- 25, 37-40, 41-44 and 43-46, correspond to several important antibody b inding sites revealed in relevant immunological research.