Laccase versus laccase-like multi-copper oxidase: a comparative study of similar enzymes with diverse substrate spectra

PLoS One. 2013 Jun 3;8(6):e65633. doi: 10.1371/journal.pone.0065633. Print 2013.

Abstract

Laccases (EC 1.10.3.2) are multi-copper oxidases that catalyse the one-electron oxidation of a broad range of compounds including substituted phenols, arylamines and aromatic thiols to the corresponding radicals. Owing to their broad substrate range, copper-containing laccases are versatile biocatalysts, capable of oxidizing numerous natural and non-natural industry-relevant compounds, with water as the sole by-product. In the present study, 10 of the 11 multi-copper oxidases, hitherto considered to be laccases, from fungi, plant and bacterial origin were compared. A substrate screen of 91 natural and non-natural compounds was recorded and revealed a fairly broad but distinctive substrate spectrum amongst the enzymes. Even though the enzymes share conserved active site residues we found that the substrate ranges of the individual enzymes varied considerably. The EC classification is based on the type of chemical reaction performed and the actual name of the enzyme often refers to the physiological substrate. However, for the enzymes studied in this work such classification is not feasible, even more so as their prime substrates or natural functions are mainly unknown. The classification of multi-copper oxidases assigned as laccases remains a challenge. For the sake of simplicity we propose to introduce the term "laccase-like multi-copper oxidase" (LMCO) in addition to the term laccase that we use exclusively for the enzyme originally identified from the sap of the lacquer tree Rhus vernicifera.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Biocatalysis
  • Catalytic Domain
  • Copper / chemistry
  • Copper / metabolism
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Fungal Proteins / chemistry
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism*
  • Laccase / chemistry
  • Laccase / genetics
  • Laccase / metabolism*
  • Molecular Sequence Data
  • Oxidation-Reduction
  • Oxidoreductases / chemistry
  • Oxidoreductases / genetics
  • Oxidoreductases / metabolism*
  • Plant Proteins / chemistry
  • Plant Proteins / genetics
  • Plant Proteins / metabolism*
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Rhus / enzymology
  • Sequence Alignment
  • Substrate Specificity
  • Terminology as Topic

Substances

  • Bacterial Proteins
  • Fungal Proteins
  • Plant Proteins
  • Recombinant Proteins
  • Copper
  • Oxidoreductases
  • Laccase
  • copper oxidase

Grant support

This work was supported by the CTI project 11647.2 PFLS-LS, http://www.kti.admin.ch. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.