The use of enzymes as catalysts has become increasingly important in many industrial applications such as food processing, detergents, textiles and organic synthesis. However, a limiting factor for the industrial application of enzymes is their poor operational or long-term stability when exposed to environmental challenges, such as elevated temperatures and pH extremes. Recent advances in atom transfer radical polymerization (ATRP) and reversible addition–fragmentation chain transfer (RAFT) enable the polymerization of acrylates and acrylamides from proteins In both cases amino acid residues are modified with chain-transfer agents or ATRP initiators and polymers grafted-from in situ. In the literature the primary residues modified are lysine, due to this residues relative surface abundance and ease of preparing activated ester CTA/ATRP initiators. Cysteine residues, although less abundant on protein surfaces can be readily reacted with alkene bearing CTA/ATRP initiators such as maleimide or acrylate. Less common residues modified include the N or C terminal or the genetic introduction of non-canonical amino acid moieties. We were interested in studying the impact of residue modification using grafting from of another common surface residue aspartic (D) or glutamic acid (E). ATRP was selected as the grafting-from strategy due to the inherent instability of an amine containing RAFT agent required for acid residue ligation. Lipase TL was modified at either lysine (K) or acid (D/E) residues and <i>N</i>-[3-(Dimethylamino)propyl]acrylamide (DMAPA) was grafted from suing ICAR ATRP. Protein activity was assessed using a colorimetric based hydrolysis assay under normal and elevated temperature. We found that the grafted TL-D/E-pDMAPA had a significantly higher activity than TL-K-pDMAPA more importantly our results indicate that this new amino acid modification strategy may be employable in other enzymes granting access to new biohybrid modification schemes.<br/>

Impact of amino acid residue on biohybrid activity: Asp/Glu Vs Lys

256th National Meeting (2018)

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