Process Biochemistry 47 (2012) 1295–1307 Contents lists available at SciVerse ScienceDirect Process Biochemistry jo u rn al hom epage: www.elsevier.com/locate/procbio Review Fungal laccases as green catalysts for dye synthesis  Jolanta Polak, Anna Jarosz-Wilkolazka ∗ Biochemistry Department, Maria Curie-Sklodowska University, Akademicka 19, 20-033 Lublin, Poland a r t i c l e i n f o Article history: Received 27 January 2012 Received in revised form 10 May 2012 Accepted 10 May 2012 Available online 22 May 2012 Keywords: Laccase Dyes Biocatalysis Biotransformation a b s t r a c t Laccases from different sources catalyse oxidation of various phenolic and aromatic compounds to prod- ucts that very often are colourful and may be used as dyes, especially in the textile industry. They catalyse not only catabolic processes such as depolymerisation and degradation but can also carry out various dimerization, oligomerization, and polymerization reactions of some hundred aromatic substrates that synthesize new molecules with valuable functions. Because of their versatile biochemical properties, high protein stability, breadth of substrate spectrum, laccases are the key enzymes having applications in biotechnological processes as eco-friendly biocatalyst. This review refers to the natural abilities of laccases to synthesize colour products with respect to the type of the enzymatic reaction, catalyst characterization and possible use of these colour products as dyestuffs. © 2012 Elsevier Ltd. All rights reserved. Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1295 2. The sources of laccases and their functions in the natural environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1296 3. The mechanism of laccase-mediated reaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1297 4. Types of laccase-mediated reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1297 4.1. Direct oxidation of substrates (the type A reaction) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1298 4.2. Oxidation of substrates in the presence of mediators (the type B reaction) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1299 4.3. Coupling of reactive intermediates (the type C reaction) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1299 5. Dyes obtained due to the laccase action . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1299 5.1. Phenolic and non-phenolic dyes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1299 5.2. Phenoxazinone compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1301 5.3. Azo dyes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1302 5.4. Dyes synthesized in situ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1302 6. Patents relating to laccase-based synthesis of coloured compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1303 7. Concluding remarks and prospects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1304 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1304 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1304 1. Introduction Nowadays, there is an increasing demand on the chemical indus- try to develop eco-friendly processes with the use of biocatalysts that represent an attractive route towards one-step safe synthe- sis. Biocatalysis not only can improve the selectivity of a reaction  This paper is in memory of Sophie Vanhulle who inspired us in the study of the use of enzymes for dye synthesis. Sophie was the scientific coordinator of the project SOPHIED and this paper is a continuation of the main subject of that large research project (2004–2008). Sophie accidentally deceased on September 12th, 2009. ∗ Corresponding author. Tel.: +48 81 537 50 44; fax: +48 81 537 51 02. E-mail address: anna.wilkolazka@poczta.umcs.lublin.pl (A. Jarosz-Wilkolazka). but, by doing so, it can also decrease or even remove the need for downstream processing, thereby reducing the material and energy waste associated with product purification. Biocatalysis has many advantages in the context of green chemistry such as mild reac- tion conditions (physiological pH and temperature) and often fewer steps than conventional chemical procedures. Consequently, classi- cal chemical procedures are being increasingly replaced by cleaner biocatalytic alternatives, especially in the fine chemicals industry. Green catalytic alternatives are particularly needed in oxidation processes, which are still carried out with inorganic (or organic) oxidants such as chromium (VI) compounds, permanganate, man- ganese dioxide, and periodate. There is clearly a definite need for catalytic alternatives employing clean primary oxidants such as 1359-5113/$ – see front matter © 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.procbio.2012.05.006