Xenoestrogenic short ethoxy chain nonylphenol is oxidized by a flavoprotein alcohol dehydrogenase from Ensifer sp. strain AS08

Xin Liu, Akio Tani, Kazuhide Kimbara, Fusako Kawai

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

The ethoxy chains of short ethoxy chain nonylphenol (NPEOav2.0, containing average 2.0 ethoxy units) were dehydrogenated by cell-free extracts from Ensifer sp. strain AS08 grown on a basal medium supplemented with NPEO av2.0. The reaction was coupled with the reduction in 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide and phenazine methosulfate. The enzyme (NPEOav2.0 dehydrogenase; NPEO-DH) was purified to homogeneity with a yield of 20% and a 56-fold increase in specific activity. The molecular mass of the native enzyme was 120 kDa, consisting of two identical monomer units (60 kDa). The gene encoding NPEO-DH was cloned, which consisted of 1,659 bp, corresponding to a protein of 553 amino acid residues. The deduced amino acid sequence agreed with the N-terminal amino acid sequence of the purified NPEO-DH. The presence of a flavin adenine dinucleotide (FAD)-binding motif and glucose-methanol-choline (GMC) oxidoreductase signature motifs strongly suggested that the enzyme belongs to the GMC oxidoreductase family. The protein exhibited homology (40-45% identity) with several polyethylene glycol dehydrogenases (PEG-DHs) of this family, but the identity was lower than those (approximately 58%) among known PEG-DHs. The substrate-binding domain was more hydrophobic compared with those of glucose oxidase and PEG-DHs. The recombinant protein had the same molecular mass as the purified NPEO-DH and dehydrogenated PEG400-2000, NPEOav2.0 and its components, and NPEOav10, but only slight or no activity was found using diethylene glycol, triethylene glycol, and PEG200.

Original languageEnglish
Pages (from-to)1414-1422
Number of pages9
JournalApplied Microbiology and Biotechnology
Volume73
Issue number6
DOIs
Publication statusPublished - Jan 1 2007

Keywords

  • Ensifer sp. strain AS08
  • Flavoprotein alcohol dehydrogenase
  • Short ethoxy chain nonylphenol

ASJC Scopus subject areas

  • Biotechnology
  • Applied Microbiology and Biotechnology

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