Polyethyleneglycol-based resins as solid supports for the synthesis of difficult or long peptides

An evaluation of the polyethyleneglycol-based ChemMatrix (R) resin as solid support for the synthesis of challenging peptide sequences is presented. Comparison with conventional polystyrene and polyethyleneglycol-polystyrene resins in several instances of typically difficult solid phase syntheses shows a consistently better performance of the ChemMatrix (R) resin in terms of end product purity. Representative test sequences include a 15-residue antibiotic, a gp41 ectodomain hybrid sequence, a calcipressin fragment with an N-terminal Arg(11) extension, and two chemokines of 69- and 64-amino acid residues. Interestingly, a difference in only five amino-acids between the two chemokine sequences had a remarkable impact on synthetic results, which in the case of the 69-residue peptide required additional refinements (beta-sheet-breaking pseudoproline dipeptides) for success.