title: Purification and characterization of a lyase from the EDTA-degrading bacterial strain DSM 9103 that catalyzes the splitting of [S,S]-ethylenediaminedisuccinate, a structural isomer of EDTA.
abstract: The bacterial strain DSM 9103, able to utilize EDTA as a sole source of carbon, nitrogen, and energy, is also capable to grow with [S,S]-ethylenediaminedisuccinate ([S,S]-EDDS), a structural isomer of EDTA. In cell-free extracts of [S,S]-EDDS-grown bacteria, [S,S]-EDDS degradation was observed in the absence of any cofactors. An enzyme was purified 41-fold that catalyzed the non-hydrolytic splitting of [S,S]-EDDS leading to the formation of fumarate and N-(2-aminoethyl) aspartic acid. These data strongly suggest that the enzyme belongs to the group of carbon-nitrogen lyases. The splitting reaction was reversible, and an equilibrium constant of approximately 43.0 10(-1) M was determined. Out of the three stereo-isomers of EDDS, [S,S]- and [R,S]-EDDS were accepted as substrates by the lyase, whereas [R,R]-EDDS remained unchanged in assays with both cell-free extracts and pure enzyme. The enzyme catalyzed the transformation of free [S,S]-EDDS and of [S,S]-EDDS-metal complexes with stability constant lower than 10, namely of MgEDDS, CaEDDS, BaEDDS and to a small extent also of MnEDDS; FeIIIEDDS, NiEDDS, CuEDDS, CoEDDS and ZnEDDS were not transformed.
authors.affiliation: Swiss Federal Institute for Environmental Science and Technology (EAWAG) and Swiss Federal Institute of Technology (ETH), CH-8600 Dübendorf, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Witschel
authors.forename: T
authors.initials: T
authors.lastname: Egli
mesh_terms: D001419:Bacteria / Q000201:enzymology* / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism; D001673:Biodegradation, Environmental; D002614:Chelating Agents / Q000378:metabolism*; D002850:Chromatography, Gel; D004492:Edetic Acid / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005029:Ethylenediamines / Q000378:metabolism*; D007536:Isomerism; D008190:Lyases / Q000737:chemistry* / Q000302:isolation & purification; D020560:Proteobacteria / Q000201:enzymology / Q000378:metabolism*; D013386:Succinates / Q000378:metabolism*
chemical_list: C499100:(S,S)-ethylenediaminedisuccinate; D001426:Bacterial Proteins; D002614:Chelating Agents; D005029:Ethylenediamines; D013386:Succinates; D004492:Edetic Acid; D008190:Lyases