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J. Bacteriol., 03 1997, 1521-1524, Vol 179, No. 5
JY Lee and L Xun
The biochemistry of pentachlorophenol (PCP) degradation by Flavobacterium
sp. strain ATCC 39723 has been studied, and two enzymes responsible for the
conversion of PCP to 2,6-dichloro-p-hydroquinone (2,6-DiCH) have previously
been purified and characterized. In this study, enzymatic activities
consuming 2,6-DiCH were identified from the cell extracts of strain ATCC
39723. The enzyme was purified to apparent homogeneity by a purification
scheme consisting of seven steps. Gel filtration chromatography showed a
native molecular weight of about 40,000, and sodium dodecyl
sulfate-polyacrylamide gel electrophoresis revealed a single protein of
42,500 Da. The purified enzyme converted 2,6-DiCH to 6-chlorohydroxyquinol
(6-chloro-1,2,4-trihydroxybenzene), which was easily oxidized by molecular
oxygen and hard to detect. The end product, 6-chlorohydroxyquinol, was
detected only in the presence of a reductase and NADH in the reaction
mixture. The enzyme dechlorinated 2,6-DiCH but not 2,5-DiCH. The enzyme
required Fe2+ for activity and was severely inhibited by metal chelating
agents. The optimal conditions for activity were pH 7.0 and 40 degrees C.
The Kcat for 2,6-DiCH was 35 microM, and the kcat was 0.011 s-1.
Copyright © 1997, American Society for Microbiology
Purification and characterization of 2,6-dichloro-p-hydroquinone chlorohydrolase from Flavobacterium sp. strain ATCC 39723
Environmental Microbiology Group, Battelle Pacific Northwest National Laboratory, Washington State University, Tri-Cities, Richland 99352, USA.
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