A Chemoselective Method for Site-Specific Immobilization of Peptides via Aminooxy Group

Site-specific modification of peptides and proteins is an important area of basic research for preparation of well-defined biosensors and probes. The unique properties of aminooxy group present an opportunity for chemoselective site-specific immobilization of peptides to prepare well-defined biosensors. We have prepared FLAG peptide derivatives containing l-ε-aminooxylysine (l-ε-AOLys, 1a) and l-lysine units in their sequence at the C- and N-terminals via solid-phase synthesis. Site-specific modification of peptides through aminooxy group was demonstrated in the preparation of biosensors and selective conjugation in the preparation of biotinylated probes. Effect of the incorporation of l-ε-AOLys (1a) into the peptide sequence and its subsequent labeling on the FLAG epitopic character was measured using a surface plasmon resonance detector. It was found that incorporation of l-ε-AOLys (1a) into the FLAG peptide and site-specific immobilization through aminooxy group preserved the integrity of FLAG epitope.