Reduction of the 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonate) cation radical by physiological organic acids in the absence and presence of Manganese

Patrick J. Collins, Alan D.W. Dobson, Jim A. Field

Research output: Contribution to journalArticle

46 Scopus citations

Abstract

Laccase is a copper-containing phenoloxidase, involved in lignin degradation by white rot fungi. The laccase substrate range can be extended to include nonphenolic lignin subunits in the presence of a noncatalytic cooxidant such as 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonate) (ABTS), with ABTS being oxidized to the stable cation radical, ABTS.+, which accumulates. In this report, we demonstrate that the ABTS.+ can be efficiently reduced back to ABTS by physiologically occurring organic acids such as oxalate, glyoxylate, and malonate. The reduction of the radical by oxalate results in the formation of H2O2, indicating the formation of O2.- as an intermediate. O2.- itself was shown to act as an ABTS.+ reductant. ABTS.+ reduction and H2O2 formation are strongly stimulated by the presence of Mn2+, with accumulation of Mn3n+ being observed. Additionally, 4-methyl-O-isoeugenol, an unsaturated lignin monomer model, is capable of directly reducing ABTS.+. These data suggest several mechanisms for the reduction of ABTS.+ which would permit the effective use of ABTS as a laccase cooxidant at catalytic concentrations.

Original languageEnglish (US)
Pages (from-to)2026-2031
Number of pages6
JournalApplied and environmental microbiology
Volume64
Issue number6
DOIs
StatePublished - Jun 1998
Externally publishedYes

ASJC Scopus subject areas

  • Biotechnology
  • Food Science
  • Applied Microbiology and Biotechnology
  • Ecology

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