Polymers laccases

Keywords Functional polymer Laccase Lignocellulose Peroxidase Abbreviations... 

What follows is a practical example demonstrating an engineering effort to improve a redox hydrogel-mediated laccase cathode meant to reduce oxygen to water in a BFC [65]. The laccase cathode is produced by combining an osmium redox polymer, laccase from Trametes versicolor, and a diepoxide cross-linker in the proportions 61, 32, and 7% by mass, respectively. After curing in a dry environment, a catalytic film is produced, which will reduce oxygen to water on an electrode surface [73,79]. 

Catechin-immobilizing polymer particles were prepared by laccase-catalyzed oxidation of catechin in the presence of amine-containing porous polymer particles. The resulting particles showed good scavenging activity toward stable free l,l-diphenyl-2-picryl-hydrazyl radical and 2,2 -azinobis(3-ethylbenzothiazoline-6-sulfonate) radical cation. These particles may be applied for packed column systems to remove radical species such as reactive oxygen closely related to various diseases. 

Figure 17.6 Redox hydrogel approach to immobilizing multiple layers of a redox enzyme on an electrode, (a) Structure of the polymer, (b) Voltammograms for electrocatalytic O2 reduction by a carbon fiber electrode modified with laccase in the redox hydrogel shown in (a) (long tether) or a version with no spacer atoms in the tether between the backbone and the Os center (short tether). Reprinted with permission fi om Soukharev et al., 2004. Copyright (2004) American Chemical Society.

Co-immobilization of this redox polymer with a fungal laccase from Trametes versicolor, possessing a Tl copper site reduction potential of +0.57 V vs Ag/AgCl ( +0.77 vs NHE), was achieved using a diepoxide cross-linker, in an approach... 

An alternative strategy for co-immobilization of mediator and GOx is based on adsorption of enzyme, cross-linked, as was described for the laccase-based biocatalytic cathodes [30, 37 42], to an osmium-based redox polymer film, on carbon electrodes [1-3, 54],... 

Wine and beer industry Polyphenols can alter color and flavor of products such as wines. There are many aggressive ways of removing polyphenolic compounds, such as using polyvinylpolypyrrolidone (PVPP) or sulfur dioxide. However, polyphenol removal should be selective to avoid the undesirable alteration of the wine s organoleptic characteristics. For this reason, one option is to use laccases that polymerize the polyphenolic compounds during the wine-making process and then to remove these polymers by clarification (Morozova and others 2007). Several papers have reported that laccase is able to remove undesirable polyphenols and produce stable wines with a good flavor. 

The production and synthesis of polymers and medical agents is one of the most interesting potential uses for laccases in synthetic chemistry, where their application has been proposed for oxidative deprotection and the production of complex polymers and pharmaceutical agents. 

Micard V and Thibault JF. 1999. Oxidative gelation of sugar-beet pectins use of laccases and hydration properties of the cross-linked pectins. Carbohyd Polym 39 265-273. 

This electrode is unique in that the bilirubin oxidase is active at neutral pH, whereas the laccase cited above is not, even though the redox potential of laccase is somewhat higher. Additionally, the bilirubin oxidase is much less sensitive to high concentrations of other anions such as chloride and bromide, which deactivate laccase. It was shown that mutations of the coordination sphere of bilirubin oxidase led to an increased redox potential of the enzyme, which increased current density and reduced current decay to 5%/day over 6 days at 300 rpm. The latter improvement was attributed to improved electrostatic attraction between the enzyme and the redox polymer. An electrode made with high-purity bilirubin oxidase and this redox polymer has recently been shown to outperform a planar platinum electrode in terms of activation potential and current density of oxygen reduction. ... 

For example, the small scale of the device was intended as a demonstration of architecture suitable for implanted applications. Mano et al. demonstrated a miniature fuel cell with bilirubin oxidase at the cathode catalyst that is more active at pH 7 and tolerates higher halide concentrations than does laccase. Additionally, the long-side-chain poly-(vinylpyridine)—Os(dialkyl-bis-imidazole)3 redox polymer discussed above was employed to both lower the anode potential and, via the long side chains, enhance electron transport from the biocatalyst. The cell achieved a current density of 830 at 0.52 V... 

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