Laccase
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
- ↑ 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 .
- ↑ Hans W. Heldt and Birgit Piechulla: Plant biochemistry . Spectrum Academic Publishing House; 4th edition 2008; ISBN 978-3-8274-1961-3 ; P. 420.
- ↑ 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