89198-07-2Relevant articles and documents
Structural Basis for the Catalytic Mechanism of Ethylenediamine- N, N′-disuccinic Acid Lyase, a Carbon-Nitrogen Bond-Forming Enzyme with a Broad Substrate Scope
Poddar, Harshwardhan,De Villiers, Jandré,Zhang, Jielin,Puthan Veetil, Vinod,Raj, Hans,Thunnissen, Andy-Mark W. H.,Poelarends, Gerrit J.
, p. 3752 - 3763 (2018/05/23)
The natural aminocarboxylic acid product ethylenediamine-N,N′-disuccinic acid [(S,S)-EDDS] is able to form a stable complex with metal ions, making it an attractive biodegradable alternative for the synthetic metal chelator ethylenediaminetetraacetic acid (EDTA), which is currently used on a large scale in numerous applications. Previous studies have demonstrated that biodegradation of (S,S)-EDDS may be initiated by an EDDS lyase, converting (S,S)-EDDS via the intermediate N-(2-aminoethyl)aspartic acid (AEAA) into ethylenediamine and two molecules of fumarate. However, current knowledge of this enzyme is limited because of the absence of structural data. Here, we describe the identification and characterization of an EDDS lyase from Chelativorans sp. BNC1, which has a broad substrate scope, accepting various mono- and diamines for addition to fumarate. We report crystal structures of the enzyme in an unliganded state and in complex with formate, succinate, fumarate, AEAA, and (S,S)-EDDS. The structures reveal a tertiary and quaternary fold that is characteristic of the aspartase/fumarase superfamily and support a mechanism that involves general base-catalyzed, sequential two-step deamination of (S,S)-EDDS. This work broadens our understanding of mechanistic diversity within the aspartase/fumarase superfamily and will aid in the optimization of EDDS lyase for asymmetric synthesis of valuable (metal-chelating) aminocarboxylic acids.
Reactivity Studies of Chelated Maleate Ion: Stereoselectivity and Structural Correlations
Hammershoei, Anders,Sargeson, Alan M.,Steffen, William L.
, p. 2819 - 2837 (2007/10/02)
cobalt(III) ion (Λ-+ (1)) undergoes parallel OH- catalyzed reactions in aqueous solutions, first order in ->, to give stereospecific addition of a 2-aminoethaneaminato ion at the chelated olefin center and thereby (R)-N-(2-aminoethyl)aspartate (R-aea) bound as a quadridentate in Λ-mer(5,5)-+ (3) (k = 0.09 M-1 s-1, 25 deg C, μ = 1 M).The other path (k = 0.36 M-1 s-1) produced cis- and trans- complexes (19, 20) where the ring-opened monodentate ligand is unreactive.Similar stereoselectivity was observed for the reaction in liquid NH3 and dimethyl sulfoxide without ring opening.Equilibrium studies established that the fac(5,5)-+ isomer was more stable (96percent) than the mer isomer (4percent) produced by kinetic control.In the alkaline conditions the mer isomer also dissociates a carboxylate group and isomerizes about the cobalt center.The kinetics of this process were also followed.X-ray crystallographic analyses of the Λ-PF6*2H2O (I), racemic ClO4*2H2O (II), and Δ-fac(5,5)-BCS*3H2O (III) (BCS- = (+)589-α-bromocamphorsulfonate anion) salts were carried out to determine their connectivities and absolute configuration by the anomalous dispersion method.For I: space group P21; a = 11.629(6) Angstroem, b = 7.701(4) Angstroem, c = 9.379(4) Angstroem, β = 97.18(1) deg, Z = 2, 4336 reflections (F2 >= 3.0?(F2)), residual R1 = 0.045.For II: space group P21/c; a = 7.191(1) Angstroem, b = 10.915(2) Angstroem, c = 20.723(6) Angstroem, β = 91.41(1) deg, Z = 4, 4796 reflections (F2 >= 3.0?(F2)), residual R1 = 0.045.For III: space group P1; a = 6.976(1) Angstroem, b = 7.242(1) Angstroem; c = 14.248(2) Angstroem, α = 76.89(1) deg, β = 84.61(1) deg, γ = 70.86(1) deg, Z=1, 4731 reflections (F2 >= 3.0?(F2)), residual R1 = 0.040.The absolute configuration of the complex cation was also deduced from that of the BCS- anion.The chiral N-(2-aminoethyl)aspartate was biologically inactive in an aspergillomarasmine sense, but the results in general provide some support for Glusker's ferrous wheel mechanism for aconitase.
