An Investigation into the Effect of Backbone Amide Linker Position on the Solid Phase Peptide Synthesis of a Cyclic Pentapeptide

A study on the impact of the position of the attachment of the photolabile, backbone amide linker, 4-formyl-3-hydroxy-5-nitrobenzoic acid, on the synthesis of a model cyclic pentapeptide was conducted. The peptide was synthesized on a solid support and cleaved photolytically. The crude product was analyzed for the effect of changing position by LC/MS, 1HNMR, and yield. The target peptide could not be identified convincingly by LC/MS or NMR. It was observed that attachment of the backbone amide linker to the N alpha of tyrosine provided the highest crude product yield.