Laccase as food enzyme:
Laccase is an enzyme that catalyses the oxidation of phenolic compounds such as ortho-and para-diphenols to their corresponding quinones, with the concomitant reduction of oxygen to water (Chivukula and Renganathan, 1995). Quinones react with specific sulphur compounds causing malodorous agents in the mouth. Therefore, laccase can be used in chewing gums and breath-freshening products as neutralizing factor. In addition, laccase is used for the supression of polyphenol in wines, and to increase storage time of beer (Tannoven and Eksi, 2005; Mathiasen, 1995). Finally, an indirect food application for laccase is developed in cork stopper preparation. The Oxidative function of laccase reduces the taint or taste coming from the cork in aged wine bottle (Conrad et al., 2000, Xu, 2005).
Laccase in biofuel cell (BFC):
The redox potential of laccase is used on cathodes of biofuel cell. The reaction produces protons and water from oxidation of dihydrogen by laccase (Blandford et al., 2009). Because of the specificity of the enzymatic reaction, BFC do not require proton exchange membrane like in traditional fuel cell. In addition, fuel and oxidant can be mixed. These advantages offer great possibilities of miniaturization of the biofuel cells (Wait et al., 2010). In addition, improvement of laccase activity for biofuel cell application was found by coupling the enzyme with nanoparticules to create a cathode (Gilaki, 2010).
Laccase in textile industry:
Demim finishing
In denim industry, removal of indigos is an essential step to give the fabric its abrasion effect. However, the chemicals used to perform this reaction are highly dangerous pollutants (Pedersen and Schneider, 1998). Laccase was shown to be able to degrade indigos and that, without mediator, Trametes vesicolor laccase was more effective in demim finishing than recombinant enzyme combined with mediator (Campos et al., 2001; Pazarlioglu et al., 2005).
Cotton bleaching/dyeing
Flavonoids are responsible for the natural color of cotton and hydrogen peroxide is industrially used to bleach this fabric (Ardon et al., 1996). However this corrosive treatment reduces the fiber quality and demand large volumes of washing water. Laccase was demonstrated to have bleaching properties at low concentrations without reducing the quality of the fabric (Tzanov et al., 2003). In addition its bleaching function, laccase was shown to enhance fixation of polymeric dye on cotton by oxidation and thereby also exhibit dyeing ability (Hadzhiyska et al., 2006).
Wool dyeing/decoulourization
Similarly to cotton dyeing, laccase capacity to enhance fixation of dye on wool was described. This coloring method presents the economical advantage of reducing the amount of dye used when deeper colors are to be obtained (Zille, 2005). Traditionally, deeper colors result from addition of dye into the coloring solution containing large amounts of water and acid. In presence of laccase, dye precursors and catechol, increase the dyeing reaction resulted in deeper color wool. Laccase is also used to decolorize wool from azo-dyes (Ryan et al., 2003).
Anti-shrink treatment for wool
Conventional treatment of wool against shrinking is chlorination which has a negative impact on environment. Therefore enzymes were tried to replace this polluting process. It was found that laccase treatment of wool fiber, together with a mediator, prevents the fabric from shrinking (Lantto et al., 2004).
Dye synthesis
Oxidative coupling of phenols with 3-methyl-2-benzothialinone hydrazone (MBTH) or oxidation of ferulic acid by laccase resulted in colored products used in dyeing processes. New dyes are currently developed from phenolic and polyphenolic substrates (Mustafa et al., 2005).
References:
Ardon O, Kerem Z and Hadar Y (1996). Enhancement of laccase activity in liquid cultures of the ligninolytic fungus Pleurotus ostreatus by cotton stalk extract. J. Biotechnol. 51: 201-207.
Blanford CF, Foster CE, Heath RS and Armstrong FA (2009). Efficient electrocatalytic oxygen reduction by the "blue" copper oxidase, laccase, directly attached to chemically modified carbons. Faraday Discuss., 2009, 140, 319 - 335.
Campos R, Kandelbauer A, Robra KH, Cavaco-Paulo A and Gübitz GM (2001). Indigo degradation with purified laccases from Trametes hirsuta and Sclerotium rolfsii J. Biotechnol. 89:131-139.
Chivukula M and Renganathan V (1995). Phenolic Azo Dye Oxidation by Laccase from Pyricularia oryzae. Appl Environ Microbiol. 1995 Dec;61(12):4374-7.
Conrad LS, Sponholz WR and Berker O (2000). US6152966 (2000).
Gilaki, M. (2010). Nano Immobilization of Enzyme to Improvement of Biofuel Cell Electrode's Function. Pak. J. Biol. Sci., 13: 611-612.
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Mathiasen TE(1995). WO9521240 A2 (1995).
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Ryan S, Schnitzhofer W, Tzanov T, Cavaco-Paulo A and Gübitz GM (2003). An acid-stable laccase from Sclerotium rolfsii with potential for wool dye decolourization. Enzyme and Microbial Technology 33 (2003) 766-774.
Schneider P.t.N.N. (1998). US Pat. 5795855 A. USPatent.
Tannoven D and Eksi A. Phenolic compounds in pear juice from different cultivars. Food Chem 2005; 93: 89-93.
Tzanov T, Basto C, Gübitz GM and Cavaco-Paulo A (2003). Laccases to improve the whiteness in a conventional bleaching of cotton. Macromol. Mater. Eng. 288: 807-810.
Wait AF, Parkin A, Morley GM, dos Santos L and Armstrong FA (2010). Characteristics of Enzyme-Based Hydrogen Fuel Cells Using an Oxygen-Tolerant Hydrogenase as the Anodic Catalyst. J. Phys. Chem. C, 2010, 114 (27), pp 12003-12009.
Xu, F. (2005) Applications of oxidoreductases: recent progress. Industrial Biotechnol. 1, 38-50.
Zille A (2005). Laccase reactions for textile applications. PhD Thesis. Universidade do Minho, Portugal.
