Synthesis of the region of 95-109 of Hepatitis B surface antigen (HBsAg) peptide and water soluble bioconjugates with polyelectrolytes

In this study, we have synthesized the 95-109 region of the antigenic part of Hepatitis B Surface Antigen (HBsAg) Peptide by using Solid Phase Peptide Synthesis (SPPS). The amino acid composition of this sequence is: WLVLLDYQGMLPVCPL. The synthesis of the 95-109 region of the highly hydrophobic and antigenic part of Hepatitis B Surface Antigen (HBsAg) Peptide was performed by Liberty Microwave Peptide Synthesizer (CEM Corp.) using Solid Phase Peptide Synthesis (SPPS) methods and Fmoc chemistry developed by B. Merrifield. For the first time, diffrently from literature, we have synthesized the region of 95-109 of the epitopes of HbsAg peptide with including Tryptophan amino acid in N-terminus of the peptide in order to have gained fluorescence properties to the peptide molecule. The final product peptide was characterized by various choromatographic methods. In our study, we have developed new approaches to get highly immunogenic peptide conjugates: Synthetic polianions carry out the carrier molecule and adjuvant roles simultaneously and used for the conjugation with the peptide molecules. Using the 95-109 region of HBsAg peptide that highly hydrophobic and containing one amino group as an antigen, has been chosen for both physicochemical researches and developing more immunogenic bioconjugates. The bioconjugates were synthesized using different activation mechanisms and the different initial molar ratios (npeptide/npolymer= 1, 3, 5, 7, 9) of the polyanions and the peptide. And physicochemical properties of the bioconjugates were investigated. Also this peptide was conjugated with synthetic polyanions by using microwave method. The structure and characterization of the synthesized conjugates was analyzed by various choromatographic and fluorometric methods such as HPLC (High Performance Liquid Chromatography), VISCOTEK (Size Exclusion Chromatography including 4 different detector: Ultra Violet, Refractive Index, Right Angle Light Scattering and Viscometer detectors) and Fluorescence Spectrometer. The mechanisms of the activation and conjugation steps and the structures of the synthesized conjugates will be discussed. Keywords: Solid phase peptide synthesis, synthetic peptides, bioconjugation, polyelectrolytes.