IDENTIFICATION OF A SEQUENCE-DEPENDENT REVERSIBLE ACYLATION OF TOSYLARGININE IN A PEPTIDYL-RESIN REACTED WITH ISONICOTINYL P-NITROPHENYLCARBONATE

Ln this paper, we report on the identification of an unexpected acylat ion that occurred on the solid phase when a peptide containing an unpr otected lysyl and a tosyl-protected arginyl residue was treated with a large excess of isonicotinyl p-nitrophenylcarbonate. NMR and matrix-a ssisted laser desorption/ionisation -post-source decay analysis of the purified peptide demonstrated the presence of one extra isonicotinylo xycarbonyl (iNoc) group located on the omega nitrogen atom of the argi nine which was adjacent to the Lys(iNoc). The desired peptide was obta ined by quantitative removal of the unwanted iNoc group during a brief treatment with diluted aqueous hydrazine. (C) Munksgaard 1998.