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A new exocellular laccase was purified from the basidio-mycete C30. LAC2 is an acidic protein (pI¼3.2) prefer-entiallyproducedupona combined inductionby copper and p-hydroxybenzoate.The spectroscopic signature (UV/visible and EPR) of this isoform is typical of multicopper oxidases, but its enzymatic and physico-chemical properties proved to be markedly different from those of LAC1, the constitutive laccase previously purified from the same organism. | Eur. J. Biochem. 269 6119-6125 2002 FEBS 2002 doi 10.1046 j.1432-1033.2002.03324.x Characterization of a low redox potential laccase from the basidiomycete C30 Aanieszka Klonowska1 Christian Gaudin2 Andre Fournel3. Marcel Asso3 Jean Le Petit2 a Michel Giorgi1 and Thierry Tron1 1Laboratoire de Bioinorganique Structurale CNRS UMR 6517 and 2Laboratoire d Ecologie Microbienne CNRS UMR 6116 Faculte des Sciences de St Jerome Marseille France 3Laboratoire de Bioenergetique et Bioingenierie des Protéines CNRS UPR9036 Marseille France A new exocellular laccase was purified from the basidio-mycete C30. LAC2 is an acidic protein pI 3.2 preferentially produced upon a combined induction by copper and p-hydroxybenzoate. The spectroscopic signature UV visible and EPR of this isoform is typical of multicopper oxidases but its enzymatic and physico-chemical properties proved to be markedly different from those of LAC1 the constitutive laccase previously purified from the same organism. In particular the LAC2 kcat values observed for the oxidation of the substrates syringaldazine kcat 65 600 min-1 ABTS 2 2-azino-bis- 3-ethylthiazoline-6-sulfonate kcat 41 000 min-1 and guaiacol kcat 75 680 min-1 are 10-40 times those obtained with LAC1 and the redox potential of its T1 copper is 0.17 V lower than that of LAC1 E 0.73 V . This is the first report on a single organism producing simultaneously both a high and a low redox potential laccase. The cDNA clac2 was cloned and sequenced. It encodes a protein of 528 amino acids that shares 69 identity 79 similarity with LAC1 and 81 identity 95 similarity with Lcc3-2 from Polyporus ciltasus AF176321-1 its nearest neighbor in database. Possible reasons for why this basidiomycete produces in vivo enzyme forms with such different behaviors are discussed. Keywords metalloenzyme copper redox potential laccase basidiomycete C30. Laccases EC 1.10.3.2 catalyze the oxidation of a large spectrum of phenolic and nonphenolic substrates with a concomitant .
