Poh, R. and Xia, X. and Bruce, I.J. and Smith, A.R.W. (2001) 2,4-Dichlorophenoxyacetate/alpha-ketoglutarate dioxygenases from Burkholderia cepacia 2a and Ralstonia eutropha JMP134. Microbios, 105 (410). pp. 43-63. ISSN 0026-2633 .
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2,4-Dichlorophenoxyacetate (2,4-D)/alpha -ketoglutarate (alpha -KG) dioxygenase has been purified to apparent homogeneity from Burkholderia cepacia strain 2a, which utilizes 2.4-D as sole carbon source. The enzyme required ferrous ions, and was a homodimer composed of subunits having an M-r of similar to 32,000. The reaction catalysed consumed one mol each of 2,4-D, alpha -KG and dioxygen, with the production of one mol each of succinate, 2,4-dichlorophenol and glyoxylate. Maximum activity was exhibited at pH 7.8 and 25 degreesC, and reactivity was enhanced by the presence of ascorbate and cysteine. Mn2+, Zn2+, Cu2+ Fe3+ and Co2+ were inhibitory, and chemical modification of the dioxygenase revealed that thiol groups were essential for activity. The enzyme was active towards other substituted phenoxyacetates, but reacted most rapidly with 2,4-D. The apparent Michaelis constants for 2,4-D and alpha -KG were 109 and 8.9 muM, respectively. The properties of this enzyme are compared with those of the 2,4-D/alpha -KG dioxygenase from Ralstonia eutropha JMP134, which exhibits a differing N-terminal amino-acid sequence, and a different temperature 'optimum', pH optimum, substrate specificity and sensitivity to thiol-binding reagents.
|Uncontrolled keywords:||2,4-D/alpha-ketoglutarate dioxygenase; B. cepacia; R. eutropha|
|Subjects:||Q Science > QR Microbiology|
|Divisions:||Faculties > Science Technology and Medical Studies > School of Biosciences|
|Depositing User:||Suzanne Duffy|
|Date Deposited:||11 Sep 2009 11:50|
|Last Modified:||11 Sep 2009 11:50|
|Resource URI:||http://kar.kent.ac.uk/id/eprint/22807 (The current URI for this page, for reference purposes)|
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