Intramolecular electron transfer in laccases

  • Farver O
  • Wherland S
  • Koroleva O
 et al. 
  • 1

    Readers

    Mendeley users who have this article in their library.
  • N/A

    Citations

    Citations of this article.

Abstract

Rate constants and activation parameters have been determined for the internal electron transfer from type 1 (T1) to type 3 (T3) copper ions in laccase from both the fungus Trametes hirsuta and the lacquer tree Rhus vernicifera, using the pulse radiolysis method. The rate constant at 298 K and the enthalpy and entropy of activation were 25 +/- 1 s(-1), 39.7 +/- 5.0 kJ.mol(-1) and -87 +/- 9 J.mol(-1) .K(-1) for the fungal enzyme and 1.1 +/- 0.1 s(-1), 9.8 +/- 0.2 kJ.mol(-1) and -211 +/- 3 J.mol(-1) .K(-1) for the tree enzyme. The initial reduction of the T1 site by pulse radiolytically produced radicals was direct in the case of T. hirsuta laccase, but occured indirectly via a disulfide radical in R. vernicifera. The equilibrium constant that characterizes the electron transfer from T1 to T3 copper ions was 0.4 for T. hirsuta laccase and 1.5 for R. vernicifera laccase, leading to full reduction of the T1 site occurring at 2.9 +/- 0.2 electron equivalents for T. hirsuta and 4 electron equivalents for R. vernicifera laccase. These results were compared with each other and with those for the same process in other multicopper oxidases, ascorbate oxidase and Streptomyces coelicolor laccase, using available structural information and electron transfer theory.

Author-supplied keywords

  • Biocatalysis
  • Carbon Dioxide/chemistry
  • Catalytic Domain
  • Copper/*chemistry
  • Databases, Protein
  • Electron Transport
  • Entropy
  • Free Radicals/chemistry
  • Fungal Proteins/chemistry/*metabolism
  • Kinetics
  • Laccase/chemistry/*metabolism
  • Models, Molecular
  • Oxidation-Reduction
  • Plant Proteins/chemistry/*metabolism
  • Pulse Radiolysis
  • Rhus/enzymology
  • Trametes/enzymology

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Authors

  • O Farver

  • S Wherland

  • O Koroleva

  • D S Loginov

  • I Pecht

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free