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@ARTICLE{Gabriel:56261,
      author       = {Gabriel, F. L. P. and Cyris, M. and Jonkers, N. and Giger,
                      W. and Günther, K. and Kohler, H.-P. E.},
      title        = {{E}lucidation of the ipso-substitution mechanism for
                      side-chain cleavage of alpha-quaternary 4-nonylphenols and
                      4-t-butoxyphenol in {S}phingobium xenophagum {B}ayram},
      journal      = {Applied and environmental microbiology},
      volume       = {73},
      issn         = {0099-2240},
      address      = {Washington, DC [u.a.]},
      publisher    = {Soc.},
      reportid     = {PreJuSER-56261},
      pages        = {3320 - 3326},
      year         = {2007},
      note         = {Record converted from VDB: 12.11.2012},
      abstract     = {Recently we showed that degradation of several nonylphenol
                      isomers with alpha-quaternary carbon atoms is initiated by
                      ipso-hydroxylation in Sphingobium xenophagum Bayram (F. L.
                      P. Gabriel, A. Heidlberger, D. Rentsch, W. Giger, K.
                      Guenther, and H.-P. E. Kohler, J. Biol. Chem.
                      280:15526-15533, 2005). Here, we demonstrate with
                      18O-labeling experiments that the ipso-hydroxy group was
                      derived from molecular oxygen and that, in the major pathway
                      for cleavage of the alkyl moiety, the resulting nonanol
                      metabolite contained an oxygen atom originating from water
                      and not from the ipso-hydroxy group, as was previously
                      assumed. Our results clearly show that the alkyl cation
                      derived from the alpha-quaternary nonylphenol
                      4-(1-ethyl-1,4-dimethyl-pentyl)-phenol through
                      ipso-hydroxylation and subsequent dissociation of the
                      4-alkyl-4-hydroxy-cyclohexadienone intermediate
                      preferentially combines with a molecule of water to yield
                      the corresponding alcohol and hydroquinone. However, the
                      metabolism of certain alpha,alpha-dimethyl-substituted
                      nonylphenols appears to also involve a reaction of the
                      cation with the ipso-hydroxy group to form the corresponding
                      4-alkoxyphenols. Growth, oxygen uptake, and 18O-labeling
                      experiments clearly indicate that strain Bayram metabolized
                      4-t-butoxyphenol by ipso-hydroxylation to a hemiketal
                      followed by spontaneous dissociation to the corresponding
                      alcohol and p-quinone. Hydroquinone effected high oxygen
                      uptake in assays with induced resting cells as well as in
                      assays with cell extracts. This further corroborates the
                      role of hydroquinone as the ring cleavage intermediate
                      during degradation of 4-nonylphenols and 4-alkoxyphenols.},
      keywords     = {Biodegradation, Environmental / Cyclohexanes: metabolism /
                      Cyclohexenes / Gas Chromatography-Mass Spectrometry /
                      Metabolic Networks and Pathways / Molecular Structure /
                      Oxygen: metabolism / Oxygen Isotopes: metabolism / Phenols:
                      metabolism / Sphingomonas: chemistry / Sphingomonas: growth
                      $\&$ development / Sphingomonas: metabolism / Cyclohexanes
                      (NLM Chemicals) / Cyclohexenes (NLM Chemicals) / Oxygen
                      Isotopes (NLM Chemicals) / Phenols (NLM Chemicals) /
                      cyclohexadienone (NLM Chemicals) / 4-nonylphenol (NLM
                      Chemicals) / 4-butoxyphenol (NLM Chemicals) / Oxygen (NLM
                      Chemicals) / J (WoSType)},
      cin          = {ICG-3},
      ddc          = {570},
      cid          = {I:(DE-Juel1)ICG-3-20090406},
      pnm          = {Terrestrische Umwelt},
      pid          = {G:(DE-Juel1)FUEK407},
      shelfmark    = {Biotechnology $\&$ Applied Microbiology / Microbiology},
      typ          = {PUB:(DE-HGF)16},
      pubmed       = {pmid:17369338},
      pmc          = {pmc:PMC1907130},
      UT           = {WOS:000246680500024},
      doi          = {10.1128/AEM.02994-06},
      url          = {https://juser.fz-juelich.de/record/56261},
}