Concerted Electron/Proton Transfer Mechanism in the Oxidation of Phenols by Laccase. Issue 18 (22nd October 2013)

• Record Type: Journal Article
• Authors: Galli, Carlo; Madzak, Catherine; Vadalà, Raffaella; Jolivalt, Claude; Gentili, Patrizia
• Is Part Of: Chembiochem. Volume 14:Issue 18(2013)
• Page Start: 2500
• Page End: 2505
• Publication Date: 2013-10-22
• Subjects: Biochemistry -- Periodicals; Molecular biology -- Periodicals; Pharmaceutical chemistry -- Periodicals; 572
• DOI: 10.1002/cbic.201300531
• Languages: English
• ISSNs: 1439-4227

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>This study aimed to assess structural requirements in the enzyme/substrate interactions that are responsible for tuning the enzymatic reactivity. To better assess the role of the aspartic residue in the substrate‐binding pocket of basidiomycete‐type laccases, we compared the catalytic efficiency of wild‐type enzymes to that of a mutant in which carboxylic acid residue Asp206 was changed to alanine. Oxidation efficiency towards phenolic substrates by laccases of <italic>Trametes villosa</italic>, <italic>Trametes versicolor</italic> and a <italic>T. versicolor</italic> D206A mutant was studied at two pH values. By the Hammett approach and Marcus analysis, we obtained unambiguous evidence that the oxidation takes place by a concerted electron/proton transfer (EPT) mechanism, and that at pH 5 (optimum pH for enzyme activity) the phenolic proton is transferred to Asp206 during the concerted electron/proton transfer process.</p> </abstract>