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Cr(II) reactivity of taurine/alpha-ketoglutarate dioxygenase.

ABSTRACT: The interaction of CrII with taurine/alpha-ketoglutarate (alphaKG) dioxygenase (TauD) was examined. CrII replaces FeII and binds stoichiometrically with alphaKG to the FeII/alphaKG binding site of the protein, with additional CrII used to generate a chromophore attributed to a CrIII-semiquinone in a small percentage of the sample. Formation of the latter oxygen-sensitive species requires the dihydroxyphenylalanine (DOPA) quinone form of Tyr-73. This preformed side chain is generated by intracellular self-hydroxylation of Tyr-73 to form DOPA, which is subsequently oxidized to the quinone. No chromophore is generated when using NaBH4-treated sample, protein isolated from anaerobically grown cells, inactive TauD variants that are incapable of self-hydroxylation, or the Y73F active mutant of TauD. A CrIII-DOPA semiquinone also was observed in the herbicide hydroxylase SdpA.

SUBMITTER: Grzyska PK

PROVIDER: S-EPMC2596585 | biostudies-literature | 2007 Nov

REPOSITORIES: biostudies-literature

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Cr(II) reactivity of taurine/alpha-ketoglutarate dioxygenase.

Grzyska Piotr K PK Hausinger Robert P RP

Inorganic chemistry 20071101 24

The interaction of CrII with taurine/alpha-ketoglutarate (alphaKG) dioxygenase (TauD) was examined. CrII replaces FeII and binds stoichiometrically with alphaKG to the FeII/alphaKG binding site of the protein, with additional CrII used to generate a chromophore attributed to a CrIII-semiquinone in a small percentage of the sample. Formation of the latter oxygen-sensitive species requires the dihydroxyphenylalanine (DOPA) quinone form of Tyr-73. This preformed side chain is generated by intracell ...[more]

PMID: 17973473

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Measuring the orientation of taurine in the active site of the non-heme Fe(II)/α-ketoglutarate-dependent taurine hydroxylase (TauD) using electron spin echo envelope modulation (ESEEM) spectroscopy.

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Global stability of an α-ketoglutarate-dependent dioxygenase (TauD) and its related complexes.

Project description:BackgroundTauD is a nonheme iron(II) and α-ketoglutarate (αKG) dependent dioxygenase, and a member of a broader family of enzymes that oxidatively decarboxylate αKG to succinate and carbon dioxide thereby activating O2 to perform a range of oxidation reactions. However before O2 activation can occur, these enzymes bind both substrate and cofactor in an effective manner. Here the thermodynamics associated with substrate and cofactor binding to FeTauD are explored.MethodsThermal denaturation of TauD and its enzyme-taurine, enzyme-αKG, and enzyme-taurine-αKG complexes are explored using circular dichroism (CD) spectroscopy and differential scanning calorimetry (DSC).ResultsTaurine binding is endothermic (+26kcal/mol) and entropically driven that includes burial of hydrophobic surfaces to close the lid domain. Binding of αKG is enthalpically favorable and shows cooperativity with taurine binding, where the change in enthalpy associated with αKG binding (δΔHcal) increases from -30.1kcal/mol when binding to FeTauD to -65.2kcal/mol when binding to the FeTauD-taurine complex.ConclusionsThe intermolecular interactions that govern taurine and αKG binding impact the global stability of TauD and its complexes, with clear and dramatic cooperativity between substrate and cofactor.General significanceThermal denaturation of TauD and its enzyme-taurine, enzyme-αKG, and enzyme-taurine-αKG complexes each exhibited increased temperature stability over the free enzyme. Through deconvolution of the energetic profiles for all species studied, a thermodynamic cycle was generated that shows significant cooperativity between substrate and cofactor binding which continues to clarity the events leading up O2 activation.

| S-EPMC5453726 | biostudies-literature

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