Research On Convergent Solid Phase Synthesis Of HIV Fusion Inhibitor FB006

Objective: To develop the method for synthesizing a long peptide such as FB006 with 34AA, using convergent solid phase peptide synthesis (CSPPS) on the basis of step-by-step solid phase peptide synthesis (SSPPS).Methods: The study was designed as four different schemes. In scheme one four separation sites on the peptide were selected to begin with 5 fragments. The protected peptide fragments synthesized by SSPPS were ligated in solid phase. Synthesized protected peptides and the condensed products were analyzed by reversed-phase high performance liquid chromatography (RP-HPLC) and mass spectrum (MS). The scheme would then be optimized based on the results of scheme one.Results: Five protected peptide fragments were successfully synthesized by SSPPS with the purity of over 80%. The condensation results indicated that two sites were not ideal because of the racemization. Therefore, these two sites were abandoned. FB006 was then divided into three fragments in scheme two. Three protected peptide fragments were successfully synthesized by SSPPS with the purity of over 80%. The condensation results suggested that one site was not suitable due to the racemization this time. Consequently, FB006 was only divided into two fragments by that ideal site in scheme three. Two protected peptide fragments were successfully synthesized by SSPPS and a complete condensation reaction was shown.Conclusion: In the two-fragment scheme, protected peptide fragments were synthesized in HBTU/HOBt/DIEA reaction system for one hour with the feed ratio of five times AA and cleaved in 30% TFE/DCM. Condensation reaction is in DIC/HOBt/DMSO system for forty eight hours with feed ratio of twice PDⅢ-1.