Protein–polymer hybrids: Conducting ARGET ATRP from a genetically encoded cleavable ATRP initiator

• Published in: European polymer journal 2013-10, Vol.49 (10), p.2919-2924
• Main Authors: Averick, Saadyah E., Bazewicz, Christopher G., Woodman, Bradley F., Simakova, Antonina, Mehl, Ryan A., Matyjaszewski, Krzysztof
• Format: Article
• Language: English
• Subjects: Applied sciences; Atom transfer radical polymerization; Biohybrid; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Polymers with particular properties; Preparation, kinetics, thermodynamics, mechanism and catalysts; Protein–polymer hybrids
• ISSN: 0014-3057; 1873-1945
• DOI: 10.1016/j.eurpolymj.2013.04.015

[Display omitted] •A genetically encoded ester non-canonical amino acid ATRP initiator was prepared.•This initiator was inserted into the 134 amino acid residue of GFP (biF-GFP).•ARGET ATRP was used to prepared a well-defined protein polymer hybrid from biF-GFP.•The protein was stable during the polymerization.•The grafted polymer was cleaved and analyzed using gel permeation chromatography. Protein–polymer hybrids are an important class of biomaterials. Described is the preparation of a genetically incorporated a non-canonical amino acid (nCAA) containing an ester linked atom transfer radical polymerization (ATRP) initiator, followed by a controlled “grafting from” polymerization. A Methanococcus jannaschii tyrosyl-tRNA synthetase/tRNACUA pair was selected to genetically encode p-bromoisobutyryloxymethyl-l-phenylalanine (biF) in response to an amber codon. This biF was directly incorporated into green fluorescent protein (GFP) at residue 134 generating biF-GFP. Activators regenerated by electron transfer (ARGET) ATRP was conducted under biologically relevant conditions to graft well-defined poly(oligo ethylene oxide methacrylate) from the biF-GFP. The biF-GFP retained its biofluorescence properties throughout the polymerization indicating the utility of ARGET ATRP for preparing protein–polymer hybrids. The presence of a base-labile ester bond in the initiator, allowed cleavage of the grafted polymer from the protein and directly analyze their molecular weight and molecular weight distribution using gel permeation chromatography (GPC). The cleaved final polymer had a Mn=27,000 and a molecular weight distribution of Mw/Mn=1.27.