The solid phase synthesis of peptides containing an arginine residue with an unprotected guanidine group

A new variant of the solid phase synthesis of arginine-containing peptides was proposed. The conditions for the attachment to the Wang polymer of N-al pha-Fmoc arginine containing a protonated guanidine group were found. We de monstrated that this attachment is accompanied by neither racemization nor the attachment of the second Arg residue. Side reactions involving the guan idine group of arginine were studied, and methods for their prevention were proposed. The comparison of the carbodiimide method with a 1-hydroxybenzot riazole additive and a modified method with the use of Kastro's reagent for the introduction of N-alpha-Fmoc-Arg residue with the unprotected guanidin e group into the growing peptide chain demonstrated the advantages of the s econd method. Bradykinin and a peptide corresponding to the 584-591 sequenc e of the transmembrane gp41 from HIV-1 were synthesized by the method propo sed here.