Enhancing solid phase synthesis by a noncovalent protection strategy - Efficient coupling of rhodamine to resin-bound peptide nucleic acids

Resins for solid-phase synthesis can affect coupling efficiencies by interacting with reactants. We have observed that polyethylene glycol- polystyrene (PEG-PS) solid support absorbs added activated fluorophores, preventing efficient labeling of peptide nucleic acids (PNAs). We now report that addition of an inexpensive unactivated fluorophore blocks the resin and allows efficient labeling. This protection strategy may have general benefits for peptide and combinatorial synthesis.