title: Characterization of the first enzyme in 2,4-dichlorophenoxyacetic acid metabolism.
abstract: This paper reviews the properties of the Alcaligenes eutrophus JMP134 tfdA gene product, the enzyme responsible for the first step in 2,4-dichlorophenoxyacetic acid (2,4-D) biodegradation. The gene was overexpressed in Escherichia coli and several of its enzymatic properties were characterized. Although this enzyme catalyzes a hydroxylation reaction, it is not a monooxygenase. Rather, TfdA is an Fe(II) and alpha-ketoglutarate-dependent dioxygenase that metabolizes the latter cosubstrate to succinate and carbon dioxide. A variety of other phenoxyacetates and alpha-ketoacids can be used by the enzyme, but the greatest catalytic efficiencies were found using 2,4-D and alpha-ketoglutarate. The enzyme possesses multiple essential histidine residues, whereas catalytically essential cysteine and lysine groups do not appear to be present.
authors.affiliation: Department of Microbiology, Michigan State University, East Lansing 48824, USA.
authors.forename: R P
authors.initials: RP
authors.lastname: Hausinger
authors.forename: F
authors.initials: F
authors.lastname: Fukumori
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000378:metabolism*; D000421:Alcaligenes / Q000201:enzymology* / Q000235:genetics; D001673:Biodegradation, Environmental; D007656:Ketoglutaric Acids / Q000378:metabolism; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D007656:Ketoglutaric Acids; D011506:Proteins; D015084:2,4-Dichlorophenoxyacetic Acid