title: Azo cyclization: peptide cyclization via azo bridge formation.
abstract: A novel method for peptide cyclization in solution: the azo cyclization is presented herein. Ring closure by forming an azo bridge was achieved in situ by connecting the corresponding side chains of para amino phenylalanine (Pap) residues to those of tyrosine or histidine residues present in the corresponding linear precursors. The reaction was performed using an initial diazotization step in acidic media followed by intramolecular azo cyclization in a mild basic media. This new method of cyclization is facile, applicable to various sequences and results in a high yield of pure products and hence is suggested as an additional method for peptide cyclization. Here we report the successful utilization of this method for the synthesis of 10 new cyclic azo peptides, derived from RGD, GnRH, Tuftsin, VIP and SV40 NLS.
authors.affiliation: Department of Organic Chemistry, Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
authors.forename: G
authors.initials: G
authors.lastname: Fridkin
authors.forename: C
authors.initials: C
authors.lastname: Gilon
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis / Q000737:chemistry; D001391:Azo Compounds / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003500:Cyclization; D006863:Hydrogen-Ion Concentration; D010456:Peptides, Cyclic / Q000138:chemical synthesis*; D011487:Protein Conformation; D012996:Solutions; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000596:Amino Acids; D001391:Azo Compounds; D010456:Peptides, Cyclic; D012996:Solutions