Selective immobilization of peptides exclusively via N-terminus cysteines by water-driven reactions on surfaces

Immobilizing peptides or proteins on bioinert surfaces enables the elucidation of ligand-receptor interaction in complex biological systems. Here, we report a highly chemoselective surface reaction that immobilizes peptides exclusively via N-terminus cysteine residue in a peptide. At pH 5.5, only N-terminus cysteines of peptides couple covalently with phenoxy amino squarate moieties presented on self-assembled monolayers (SAMs) of alkanethiols on gold films. The selectivity of this surface reaction can tolerate the presence of internal cysteines in close proximity to basic residues such as histidines. We demonstrated this selective surface reaction by mammalian cell adhesion and by SAMDI mass spectroscopy of the SAMs.