These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Catalytic properties of the 3-chlorocatechol-oxidizing 2, 3-dihydroxybiphenyl 1,2-dioxygenase from Sphingomonas sp. strain BN6.
    Author: Riegert U, Heiss G, Kuhm AE, Müller C, Contzen M, Knackmuss HJ, Stolz A.
    Journal: J Bacteriol; 1999 Aug; 181(16):4812-7. PubMed ID: 10438749.
    Abstract:
    The 2,3-dihydroxybiphenyl dioxygenase from Sphingomonas sp. strain BN6 (BphC1-BN6) differs from most other extradiol dioxygenases by its ability to oxidize 3-chlorocatechol to 3-chloro-2-hydroxymuconic semialdehyde by a distal cleavage mechanism. The turnover of different substrates and the effects of various inhibitors on BphC1-BN6 were compared with those of another 2,3-dihydroxybiphenyl dioxygenase from the same strain (BphC2-BN6) as well as with those of the archetypical catechol 2,3-dioxygenase (C23O-mt2) encoded by the TOL plasmid. Cell extracts containing C23O-mt2 or BphC2-BN6 converted the relevant substrates with an almost constant rate for at least 10 min, whereas BphC1-BN6 was inactivated significantly within the first minutes during the turnover of all substrates tested. Furthermore, BphC1-BN6 was much more sensitive than the other two enzymes to inactivation by the Fe(II) ion-chelating compound o-phenanthroline. The reason for inactivation of BphC1-BN6 appeared to be the loss of the weakly bound ferrous ion, which is the cofactor in the catalytic center. A mutant enzyme of BphC1-BN6 constructed by site-directed mutagenesis showed a higher stability to inactivation by o-phenanthroline and an increased catalytic efficiency for the conversion of 2,3-dihydroxybiphenyl and 3-methylcatechol but was still inactivated during substrate oxidation.
    [Abstract] [Full Text] [Related] [New Search]