Characterization of an intradiol dioxygenase involved in the biodegradation of the chlorophenoxy herbicides 2,4‐D and 2,4,5‐T

FEBS Letters

Golovleva, L.A¹  Scozzafava, A²  Travkin, V.M¹  Briganti, F²  Jadan, A.P¹ 

[1] Institute of Biochemistry and Physiology of Microorganisms, Prospect Nauka 5, Russian Academy of Sciences, 142292 Pushchino, Moscow Region, Russia;University of Florence, Department of Chemistry, Via Capponi 7, 50121 Florence, Italy

关键词: Hydroxyquinol 1;    2-dioxygenase;    Intradiol dioxygenase;    Chlorophenoxyalkanoic herbicide;    2;    4-D;    2;    4;    5-T;    Nocardioides simplex;    2;    4-D;    2;    4-dichlorophenoxyacetate;    2;    4;    5-T;    2;    4;    5-trichlorophenoxyacetate;    HQ;    hydroxyquinol;    CHQ;    chlorohydroxyquinol;    HQ 1;    2-DO;    hydroxyquinol 1;    2-dioxygenase;    CHQ 1;    2-DO;    chlorohydroxyquinol 1;    2-dioxygenase;    2;    4;    5-TCP;    2;    4;    5-trichlorophenol;    EPR;    electron paramagnetic resonance;   

DOI  :  10.1016/S0014-5793(97)00297-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Hydroxyquinol 1,2-dioxygenase, an intradiol dioxygenase, which catalyzes the cleaving of the aromatic ring of hydroxyquinol, a key intermediate of 2,4-D and 2,4,5-T degradation, was purified from Nocardioides simplex 3E cells grown on 2,4-D as the sole carbon source. This enzyme exhibits a highly restricted substrate specificity and is able to cleave hydroxyquinol (K _m for hydroxyquinol as a substrate was 1.2 μM, V _max 55 U/mg, K _cat 57 s⁻¹ and K _cat/K _m 47.5 μM s⁻¹), 6-chloro- and 5-chlorohydroxyquinol. Different substituted catechols and hydroquinones are not substrates for this enzyme. This enzyme appears to be a dimer with two identical 37-kDa subunits. Protein and iron analyses indicate an iron stoichiometry of 1 iron/65 kDa homodimer, α₂ Fe. Both the electronic absorption spectrum which shows a broad absorption band with a maximum at 450 nm and the electron paramagnetic resonance spectra are consistent with a high-spin iron(III) ion in a rhombic environment typical of the active site of intradiol cleaving enzymes.

【 授权许可】

Unknown