title: Synthesis of different types of dipeptide building units containing N- or C-terminal arginine for the assembly of backbone cyclic peptides.
abstract: Different types of dipeptide building units containing N- or C-terminal arginine were prepared for synthesis of the backbone cyclic analogues of the peptide hormone bradykinin (BK: Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg). For cyclization in the N-terminal sequence N-carboxyalkyl and N-aminoalkyl functionalized dipeptide building units were synthesized. In order to avoid lactam formation during the condensation of the N-terminal arginine to the N-alkylated amino acids at position 2, the guanidino function has to be deprotected. The best results were obtained by coupling Z-Arg(Z)2-OH with TFFH/collidine in DCM. Another dipeptide building unit with an acylated reduced peptide bond containing C-terminal arginine was prepared to synthesize BK-analogues with backbone cyclization in the C-terminus. To achieve complete condensation to the resin and to avoid side reactions during activation of the arginine residue, this dipeptide unit was formed on a hydroxycrotonic acid linker. HYCRAM technology was applied using the Boc-Arg(Alloc)2-OH derivative and the Fmoc group to protect the aminoalkyl function. The reduced peptide bond was prepared by reductive alkylation of the arginine derivative with the Boc-protected amino aldehyde, derived from Boc-Phe-OH. The best results for condensation of the branching chain to the reduced peptide bond were obtained using mixed anhydrides. Both types of dipeptide building units can be used in solid-phase synthesis in the same manner as amino acid derivatives.
authors.affiliation: Friedrich-Schiller-Universität Jena, Institut für Biochemie und Biophysik, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Schumann
authors.forename: L
authors.initials: L
authors.lastname: Seyfarth
authors.forename: G
authors.initials: G
authors.lastname: Greiner
authors.forename: S
authors.initials: S
authors.lastname: Reissmann
mesh_terms: D000215:Acylation; D001120:Arginine / Q000737:chemistry*; D001920:Bradykinin / Q000737:chemistry*; D003500:Cyclization; D004151:Dipeptides / Q000138:chemical synthesis* / Q000737:chemistry; D010456:Peptides, Cyclic / Q000138:chemical synthesis* / Q000737:chemistry; D011487:Protein Conformation
chemical_list: D004151:Dipeptides; D010456:Peptides, Cyclic; D001120:Arginine; D001920:Bradykinin