ENTRY       EC 1.10.3.2
NAME        Laccase
            Urushiol oxidase
CLASS       Oxidoreductases
            Acting on diphenols and related substances as donors
            With oxygen as acceptor
SYSNAME     Benzenediol:oxygen oxidoreductase
REACTION    4 Benzenediol + O2 = 4 Benzosemiquinone + 2 H2O
SUBSTRATE   Benzenediol
            O2
            E-Coniferyl alcohol
            Catechol
            P-Benzenediol
            Aminophenol
            Phenylenediamine
PRODUCT     Benzosemiquinone
            H2O
            (+)-Pinoresinol
COFACTOR    Copper
COMMENT     A group of multi-copper proteins of low specificity acting on both
            catechol and p-benzenediol, and often acting also on aminophenols
            and phenylenediamine. The semiquinone may react further either
            enzymically or non-enzymically.
            With peroxidase, this enzyme composes of the lignin and lignan 
            biosynthesis enzyme system in plants.  E-Coniferyl alcohol is 
            converted to (+)-pinoresinol with regio- and stereospecificity.  
            The reactions catalyzed by these enzymes proceed by bimolecular 
            phenoxy radical coupling.  Stereospecificity is retained by a 
            78-kilodalton dirigent protein which is lacking catalytic activity
            and involved in capture of E-coniferyl alcohol-derived free-radical
            intermediates.
MOTIF       PS: PS00079  G-x-[FYW]-x-[LIVMFYW]-x-[CST]-x(8)-G-[LM]-x(3)-
                         [LIVMFYW]
            PS: PS00080  H-C-H-x(3)-H-x(3)-[AG]-[LM]
DBLINKS     University of Geneva ENZYME DATA BANK: 1.10.3.2
            WIT (What Is There) Metabolic Reconstruction: 1.10.3.2
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