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Unprecedented Enzymatic Synthesis of Perfectly Structured Alternating Copolymers via “Green” Reaction Cocatalyzed by Laccase and Lipase Compartmentalized within Supramolecular Complexes

Scheibel, Dieter M., Gitsov, Ivan
Biomacromolecules 2018 v.20 no.2 pp. 927-936
Burkholderia cepacia, Candida rugosa, Penicillium, catalytic activity, catechol, composite polymers, copolymerization, enzymatic reactions, fluorescence, image analysis, laccase, micelles, molecular weight, oxidation, pH, quinones, triacylglycerol lipase
This study describes the first use of laccase–lipase enzymatic reaction for the synthesis of novel perfectly structured alternating copolymers. Initially, six types of complexing agents, linear₍A₎–linear₍B₎, linear₍A₎–linear₍B₎–linear₍A₎, linear–dendritic, dendritic–linear–dendritic, linear–hyperbranched, and hyperbranched–linear–hyperbranched amphiphilic block copolymers, are proven to significantly enhance enzyme activity of three different types of lipases - Penicillium camemberti, Candida rugosa, and Burkholderia cepacia (up to 1400%, 1700%, and 870% increase with respect to the native enzymes). The copolymerization is performed in several consecutive steps: (a) lipase and laccase are dissolved in aqueous medium at neutral pH; (b) a complexing agent is added leading to cocompartmentalization of the two enzymes within a micelle or physical network; (c) the two comonomers are introduced simultaneously to the tandem enzyme complex. The reaction proceeds in the following pathway: laccase catalyzes the oxidation of catechol to o-quinone followed by lipase comediated Michael addition of a diamine. While laccase could catalyze the entire process, addition of lipase is able to increase copolymer yield up to 30.7%. Addition of a complexing agent improves the yield further up to 67.9% (23.2% yield obtained for native laccase). Complexing agents significantly increase polymer molecular mass (Mw = 130 900 vs 35 500 Da for the native enzymes reaction system). The resulting copolymers are highly fluorescent (quantum yield up to 0.733) and demonstrate pH sensitive behavior, properties that hint toward their potential as imaging agents.