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Published on: April 22, 2016
Horseradish peroxidase as a catalyst for atom transfer radical polymerization
Severin J Sigg1, Farzad Seidi, Kasper Renggli
1Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland.
Macromolecular Rapid Communications
|August 16, 2011
Summary
Horseradish peroxidase (HRP) exhibits novel ATRPase activity, catalyzing N-isopropylacrylamide polymerization without peroxide. This enzyme-mediated process yields low polydispersity polymers, with outcomes influenced by pH and reducing agent concentration.
Area of Science:
- Biocatalysis
- Polymer Chemistry
- Enzymology
Background:
- Horseradish peroxidase (HRP) is a well-known hemoprotein enzyme.
- Atom Transfer Radical Polymerization (ATRP) is a controlled polymerization technique.
- Peroxides are typically required for HRP-catalyzed reactions.
Purpose of the Study:
- To investigate a novel catalytic activity of HRP in polymerization.
- To explore the potential of HRP in controlled radical polymerization under specific conditions.
- To characterize the polymerization of N-isopropylacrylamide mediated by HRP.
Main Methods:
- Activators Regenerated by Electron Transfer Atom Transfer Radical Polymerization (ARGET ATRP) conditions were employed.
- N-isopropylacrylamide was polymerized using an alkyl bromide initiator.
- The reaction was catalyzed by horseradish peroxidase (HRP) in the absence of peroxide.
- Kinetic studies, molecular weight evolution, and polydispersity index (PDI) analysis were performed.
- The influence of pH and sodium ascorbate concentration was investigated.
Main Results:
- HRP demonstrated a novel catalytic activity, termed ATRPase activity, for N-isopropylacrylamide polymerization.
- Bromine-terminated polymers with low polydispersity indices (PDIs) down to 1.44 were successfully synthesized.
- Polymerization kinetics followed first-order behavior.
- Deviations in molecular weight and PDI evolution at increasing conversions were observed compared to standard ATRP.
- Polymerization outcomes were dependent on pH and sodium ascorbate concentration.
- HRP remained stable and did not undergo unfolding or conjugation during the process.
Conclusions:
- Horseradish peroxidase possesses a previously unrecognized ATRPase activity, enabling controlled polymerization.
- This enzyme-catalyzed polymerization offers a novel route to synthesize well-defined polymers.
- The process is sensitive to reaction conditions such as pH and reducing agent concentration, offering tunable control.
- HRP's stability under polymerization conditions highlights its potential as a robust biocatalyst.
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