Site-Selective Protein Immobilization on Polymeric Supports through N-Terminal Imidazolidinone Formation

Protein immobilization techniques on polymeric supports have enabled many applications in biotechnology and materials science. Attaching the proteins with controlled orientations has inherent advantages, but approaches for doing this have been largely limited to cysteine or noncanonical amino acid targeting. Herein, we report a method to attach the N-terminal positions of native proteins to polymer resins site-specifically through the use of 2-pyridinecarboxyaldehyde (2PCA) derivatives. For high protein loadings and practical synthesis, we initiated this work by preparing highly reactive 2PCA derivatives using Pd-catalyzed cross-coupling amination. The resulting compounds were attached to amine-containing polyethylene glycol acrylamide resin (PEGA-NH₂), which subsequently reacted with the N-termini of proteins to produce linkages that were stable over the long term but could be reversed through the addition of hydroxylamine. We envision that this site-selective, 2PCA-based protein immobilization can provide a simple and generalizable immobilization protocol.