In the last few years a lot attention has been drawn to Laccases due to their ability to oxidise both phenolic and nonphenolic lignin related compounds as well as highly recalcitrant environmental pollutants. This makes them very useful for applications concernig several biotechnological processes. This includes the detoxification of industrial effluents, for example the paper and pulp, textile and petrochemical industries, the useage as a tool for medical diagnostics and as a bioremediation agent to clean up herbicides, pesticides and certain explosives in soil.Laccases are also used as catalysts for the manufacture of anti-cancer drugs and even as ingredients in cosmetics[1]
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In our project Laccases are used as cleaning agents for a water purification systems. Their capacity to remove xenobiotic substances and produce polymeric products makes them a useful tool for bioremediation purposes."
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Laccases are copper-containing polyphenol oxidase enzymes '''(EC 1.10.3.2)''' that are found in many plants, insects, microorganisms and mainly in fungi. These enzymes are used in different metabolic pathways and fulfill several functions. E.g. these Enzymes are necessary on the one hand to degrade Lignin in ''Basidiomycetes'' and on the other hand to synthesize complex polymers like Melanin in ''Ascomycentes''.In General, laccases are extracellular enzyms and consists usually of 15-20 % carbon-hydrogen. The molecular weight of the deglycated protein is 60 to 80 kDa (about 480-650 aminoacids). These enzymes can occur as monomers, dimers, trimers and tetramers. The first crystal structure of a laccase from the organism ''Trametes versicolor''was published in 2002.
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Laccases are able to oxidize a broad range of substrates due to the contained copper-cluster, by reducing oxygen to water. The active site of the enzym includes a four-copper-ion-cluster, which can be differed by spectroscopically analyses. This Cluster consists of one blue copper-ion (type 1), one type 2 copper ions and two type 3 copper-ions. Because of the blue copper-ion, the laccases belongs to the big family of the blue copper proteins. This specific blue copper ion is essential for the radical oxidation of the phenolic group. In the enzyme-reaction the electron from the oxidation is transferred to the other three copper ions. These ions are forming a trinuclearic cluster, which transfers electrons to the terminal electron acceptor oxygen. The molecular oxygen is reduced by four electrons to water.
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[1] Susana Rodríguez Couto & José Luis Toca Herrera;<i>Industrial and biotechnological applications of laccases: A review</i>; 2006; Biotechnology Advances 24 500–513
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