Laccase

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Laccases ( EC  1.10.3.2 ) are copper-containing , "blue" enzymes that occur in many plants , fungi and microorganisms . The first laccase was isolated as early as 1883 from the sap of the Japanese lacquer tree ( Rhus vernicifera ). Hence the name laccase was chosen for this enzyme. Laccases have been detected in the biological domains of eukaryotes and prokaryotes ; They are ubiquitous in white rot fungi , but also occur in woody plants , where they are involved in lignin synthesis , as well as in some insects (e.g. wasp venom ) and bacteria (e.g. Bacillus subtilis ). Laccases catalyze the coupled oxidation of phenolic substances with the reduction of oxygen . The phenolic group is oxidized to a radical, while oxygen is reduced to water:

Laccases are thus among the oxidoreductases ; because of their substrate specificity, they are also referred to as monophenol oxidase . The catalytically active center contains four copper ions, which can be differentiated according to their spectroscopic properties. The “blue” type 1 copper ion is involved in substrate oxidation; one type 2 and two type 3 copper ions form a trinuclear cluster that binds oxygen and reduces it to water. The first crystal structure of a laccase was published in 2002; it comes from the Trametes versicolor fungus .

Active laccases can easily be detected because they are able to oxidize the chromogenic substrates ABTS , syringaldazine and guaiacol .

Laccases are used industrially for the bleaching of cellulose in the paper industry, the bleaching of textile dyes, in the production of wine corks and in other applications.

Individual evidence

  1. ↑ Yoshida, H. (1883): LXIII. — Chemistry of lacquer (Urushi). Part I. Communication from the Chemical Society of Tokyo . In: Journal of the Chemical Society, Transactions 43 , 472-486, doi : 10.1039 / CT8834300472 .
  2. ↑ Hans W. Heldt and Birgit Piechulla: Plant biochemistry . Spectrum Academic Publishing House; 4th edition 2008; ISBN 978-3-8274-1961-3 ; P. 420.
  3. ↑ Piontek, K. et al . (2002): Crystal structure of a laccase from the fungus Trametes versicolor at 1.90-A resolution containing a full complement of coppers . In: J Biol Chem . 277 (40); 37663-37669; PMID 12163489 ; PDF (free full text access).

literature

  • Morozova, OV. et al . (2007): "Blue" laccases . In: Biochemistry (Mosc) . 72 (10); 1136-1150; PMID 1802107 ; PDF (free full text access, English)
  • Ullrich, R. and Hofrichter, M. (2007): Enzymatic hydroxylation of aromatic compounds . In: Cell Mol Life Sci . 64 (3); 271-293; PMID 17221166 ; doi : 10.1007 / s00018-007-6362-1
  • Rodríguez Couto, S. and Toca Herrera, JL. (2006): Industrial and biotechnological applications of laccases: a review . In: Biotechnol Adv . 24 (5); 500-513; PMID 16716556 ; doi : 10.1016 / j.biotechadv.2006.04.003