Properties of native and hydrophobic laccases immobilized in the liquid-crystalline cubic phase on electrodes

Research output: Contribution to journalArticle

Abstract

Both native Trametes hirsuta laccase and the same laccase modified with palmytic chains to turn it more hydrophobic were prepared and studied with cyclic voltammetry and Raman spectroscopy. Native laccase immobilized in the monoolein cubic phase was characterized with resonance Raman spectroscopy, which demonstrated that the structure at the "blue" copper site of the protein remained intact. The diamond-type monoolein cubic phase prevents denaturation of enzymes on the electrode surface and provides contact of the enzyme with the electrode either directly or through the mediation by electroactive probes. Direct electron transfer for both laccases incorporated into a lyotropic liquid crystal was obtained under anaerobic conditions, whereas bioelectrocatalytic activity was shown only for the native enzyme. The differences in electrochemical behavior of native and hydrophobic laccase as well as possible mechanisms of direct and mediated electron transfers are discussed. The Michaelis constant for 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) diammonium salt (ABTS(2-)), K-M(app), and the maximal current, I-max, for the native enzyme immobilized onto the electrode were estimated to be 0.24 mM, and 5.3 mu A, respectively. The maximal current density and the efficiency of the catalysis, I (max)/K-M(app), were found to be 73 mu A cm(-2) and 208.2 mu A cm(-2) mM(-1), respectively, and indicated a high efficiency of oxygen electroreduction by the enzyme in the presence of ABTS(2-) in the cubic-phase environment. Rate constants were calculated to be 7.5 x 10(4) and 3.6 x 10(4) M-1 s(-1) for native and hydrophobic laccase, respectively.

Details

Authors
  • Ewa Nazaruk
  • Agnieszka Michota
  • Jolanta Bukowska
  • Sergey Shleev
  • Lo Gorton
  • Renata Bilewicz
Organisations
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Analytical Chemistry

Keywords

  • diammonium salt, oxygen reduction, 2, 2'-azinobis(3-ethylbenzothiazoline-6-sulfonate), laccase, voltammetry
Original languageEnglish
Pages (from-to)335-344
JournalJournal of Biological Inorganic Chemistry
Volume12
Issue number3
Publication statusPublished - 2007
Publication categoryResearch
Peer-reviewedYes

Bibliographic note

The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Analytical Chemistry (S/LTH) (011001004)