Appl. Environ. Microbiol., Jul 1995, 2453-2460, Vol 61, No. 7
M Latus, H Seitz, J Eberspacher and F Lingens
Hydroxyquinol 1,2-dioxygenase was purified from cells of the soil bacterium
Azotobacter sp. strain GP1 grown with 2,4,6-trichlorophenol as the sole
source of carbon. The presumable function of this dioxygenase enzyme in the
degradative pathway of 2,4,6-trichlorophenol is discussed. The enzyme was
highly specific for 6-chlorohydroxyquinol
(6-chloro-1,2,4-trihydroxybenzene) and hydroxyquinol
(1,2,4-trihydroxybenzene) and was found to perform ortho cleavage of the
hydroxyquinol compounds, yielding chloromaleylacetate and maleylacetate,
respectively. With the conversion of 1 mol of 6-chlorohydroxyquinol, the
consumption of 1 mol of O(inf2) and the formation of 1 mol of
chloromaleylacetate were observed. Catechol was not accepted as a
substrate. The enzyme has to be induced, and no activity was found in cells
grown on succinate. The molecular weight of native hydroxyquinol
1,2-dioxygenase was estimated to 58,000, with a sedimentation coefficient
of 4.32. The subunit molecular weight of 34,250 indicates a dimeric
structure of the dioxygenase enzyme. The addition of Fe(sup2+) ions
significantly activated enzyme activity, and metal-chelating agents
inhibited it. Electron paramagnetic resonance data are consistent with
high-spin iron(III) in a rhombic environment. The NH(inf2)-terminal amino
acid sequence was determined for up to 40 amino acid residues and compared
with sequences from literature data for other catechol and chlorocatechol
dioxygenases.
Copyright © 1995, American Society for Microbiology
Purification and Characterization of Hydroxyquinol 1,2-Dioxygenase from Azotobacter sp. Strain GP1
Universitat Hohenheim, Institut fur Mikrobiologie, 70593 Stuttgart, Germany
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