Synthesis of the protected tridecapeptide (56–68) of the VH domain of mouse myeloma immunoglobulin M603 and its reattachment to resin supports

A protected tridecapeptide, representing a new peptide corresponding to residues 56–68 of the V_H domain in the mouse M603 myeloma protein, has been prepared by solid phase peptide synthesis. The protected tridecapeptide was prepared using the photolabile 4-bromomethyl-(3-nitro)-benzamidomethyl-resin and the multidetachable 2-[4-bromomethyl)phenylacetoxy] propionyl-resin as solid supports. The synthetic protocol and protecting groups were the same for both syntheses. The protected tridecapeptide was removed photolytically from both supports and the sequence integrity was determined by preview analysis using the solid phase Edman degradation procedure. The protected tridecapeptide-OMPA was purified to homogeneity by DMF/H₂O precipitation and LH-60 chromatography. The purity of the protected peptide was further demonstrated by high pressure liquid chromatography on the free peptide after HF deprotection. The protected tridecapeptide was reattached to 4-bromomethyl-(3-nitro)-benzamidomethyl-resin to give the photolabile Boc-(protected) peptidyl-4 - oxymethyl - (3 - nitro) benzamidomethyl - resin in 25% yield. The protected tridecapeptide-oxymethylphenylacetic acid derivative was reattached to aminomethyl-resin to give Boc -(protected)peptidyl-2-[(4-oxymethyl)phenyl]acet-amidomethyl-resin in 45% yield and to 2-bromopropionyl-resin generating the multidetachable Boc - (protected)peptidyl - 2 - [(4 - oxymethyl) phenylacetoxy] propionyl-resin in 80% yield. The reactivity of these reattached peptides was demonstrated by the quantitative coupling of Boc-leucine to the protected peptide-resin. The advantages and disadvantages of the different resins with respect to solid phase fragment synthesis are discussed.