LIQUID PHASE SYNTHESIS METHOD FOR OXYTOCIN USING POLYPEPTIDES

The present disclosure discloses a liquid-phase synthesis method of oxytocin under mild conditions for the first time, which is characterized in that three oxytocin fragments which include Boc-Cys(Acm)-Tyr(tBu)-OH, H-Ile-Gln(Trt)-Asn(Trt)-Cys(Acm)-Pro-OMe and H-Leu-Gly-NH 2 are synthesized for the first time, the fragments are assembled to synthesize an all-protected oxytocin amino acid sequence, iodine is used to remove Acm while cyclization is performed to form a disulfide bond to obtain protected cyclic oxytocin, trifluoroacetic acid is used to remove residual protecting groups to obtain crude oxytocin, ethyl acetate is used to perform recrystallization, and reversed-phase chromatography purification is performed to reach high-purity (crude product purity reaches 95%) and high biological value of oxytocin (588IU/mg)._In the present invention, a Boc-polypeptide synthesis and Fmoc -polypeptide synthesis combined method is provided, wherein, all the reactions are carried out under mild conditions without using the ammonia-sodium-method decapping reaction which is reported by literature referring to oxytocin liquid-phase synthesis in domestic and abroad. Further more, the liquid-phase synthesis method of oxytocin is first performed without highly toxic reagents and unsafe reaction conditions, thus greatly reducing the cost of oxytocin synthesis and providing access to industrial production of oxytocin.