Concerted electron/proton transfer mechanism in the oxidation of phenols by laccase
2013
Galli, Carlo | Madzak, Catherine | Vadala, Raffaella | Jolivalt, Claude | Gentili, Patrizia | Institute of Chemical Methodologies - Department of Chemistry, Reaction Mechanisms Unit ; Università degli Studi di Roma "La Sapienza" = Sapienza University [Rome] (UNIROMA)-National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR) | MICrobiologie de l'ALImentation au Service de la Santé (MICALIS) ; Institut National de la Recherche Agronomique (INRA)-AgroParisTech | Laboratoire Charles Friedel ; Université Pierre et Marie Curie - Paris 6 (UPMC)-Ecole Nationale Supérieure de Chimie de Paris - Chimie ParisTech-PSL (ENSCP) ; Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Institut de Chimie - CNRS Chimie (INC-CNRS)-Centre National de la Recherche Scientifique (CNRS) | Institute of Chemical Methodologies - Department of Chemistry, Reaction Mechanisms Unit ; Università degli Studi di Roma "La Sapienza" = Sapienza University [Rome] (UNIROMA)-National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR)
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 Trametes villosa, Trametes versicolor and a T. versicolor 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.
Show more [+] Less [-]AGROVOC Keywords
Bibliographic information
This bibliographic record has been provided by Institut national de la recherche agronomique