Formation and scission of the imidazolate-bridge linkage in binuclear copper(II) complex with glycylglycine as a function of pH in aqueous solution

Sato, Massaki; Ikeda, M.; Fukuda, Masako; Ikeda, Tetsuro; Nakaya, Jun-ichi

doi:10.1016/s0020-1693(00)85561-9

Cited by 11 publications

(8 citation statements)

References 23 publications

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“…Glycylglycine (GlyGly) forms a chelation compound with Cu 2+ (GlyGly−Cu 2+ ) that further binds to deprotonated imidazole (imidazolate, Im − ) at a 2:1 molar ratio to form an imidazolate-bridged binuclear complex, (GlyGly−Cu 2+ ) 2 −Im − . 30 We mixed GlyGly−Cu 2+ with L-His instead of imidazole to prepare an analogous compound, (GlyGly−Cu 2+ ) 2 −His − , in which deprotonated His was expected to bridge two Cu 2+ ions (His − −Cu 2 ). The replacement of imidazole by L-His was necessary because the vibrations of imidazole significantly differ from those of His, and the imidazole complex is not suited for the analysis of Raman spectra of proteins.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

“…The pH of the solution was adjusted to 10.7 with NaOH to stabilize the binuclear complex. 30 After lyophilization, the complex was dissolved in D 2 O at a concentration of 1.4 mM. The pD of the final solution was adjusted to 10.7 by adding NaOD.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

“…The solution was lyophilized, and the solid product was dissolved in D 2 O at a concentration of 1.4 mM and pD 10.5. Glycylglycine (GlyGly) forms a chelation compound with Cu 2+ (GlyGly–Cu 2+ ) that further binds to deprotonated imidazole (imidazolate, Im – ) at a 2:1 molar ratio to form an imidazolate-bridged binuclear complex, (GlyGly–Cu 2+ ) 2 –Im – . We mixed GlyGly–Cu 2+ with l -His instead of imidazole to prepare an analogous compound, (GlyGly–Cu 2+ ) 2 –His – , in which deprotonated His was expected to bridge two Cu 2+ ions (His – –Cu 2 ).…”

Section: Materials and Methodsmentioning

confidence: 99%

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Pro-Oxidant Copper-Binding Mode of the Apo Form of ALS-Linked SOD1 Mutant H43R Denatured at Physiological Temperature

2013

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The mutation of Cu,Zn-superoxide dismutase (SOD1), a major antioxidant enzyme, is associated with amyotrophic lateral sclerosis (ALS). In a previous study, we showed that the metal-depleted apo form of an ALS-linked mutant, H43R, undergoes denaturation at physiological temperature (37 °C) in 90 min and acquires pro-oxidant activity in the presence of Cu(2+) and H2O2. In this study, we have examined the Cu(2+)-binding mode of denatured apo-H43R by circular dichroism (CD), fluorescent oxidation, UV Raman spectroscopy, and photooxidation. CD spectroscopy indicates that denatured apo-H43R loses native β-barrel structure and the binding of Cu(2+) to the denatured apo form induces local refolding. Fluorescent-oxidation assays in the absence and presence of Cu(2+) chelators show that denatured apo-H43R contains two Cu(2+)-binding sites with higher and lower Cu(2+) affinities and with pro-oxidant activities in the reverse order. UV Raman spectroscopy gives evidence that His residues are bound to Cu(2+) mainly through the imidazole Nτ atom at the higher-affinity site and through the Nπ atom at the lower-affinity site, sharing one His residue with each other. The Cu(2+)-binding mode of denatured apo-H43R is analogous to but different from the Cu,Zn-binding mode of the native holo form. Photooxidation experiments confirm the involvement of His residues in the pro-oxidant activity. Taken together, it is suggested that the binding of Cu(2+) induces the local refolding of denatured apo-H43R to create toxic catalytic centers that convert the enzyme from antioxidant to pro-oxidant, leading to the pathogenesis of ALS. His residues are essential for both Cu(2+)-binding and pro-oxidant activities.

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Section: ■ Materials and Methodsmentioning

confidence: 99%

Section: ■ Materials and Methodsmentioning

confidence: 99%

Section: Materials and Methodsmentioning

confidence: 99%

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Pro-Oxidant Copper-Binding Mode of the Apo Form of ALS-Linked SOD1 Mutant H43R Denatured at Physiological Temperature

2013

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“…The deprotonated form of imidazole can serve as a bridging ligand for transition metal ions [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] . Imidazolate-bridged binuclear metal complexes like bovine superoxide dismutase [Cu(II)-Im-Zn(II)SOD] 16 are of much interest.…”

Section: Introductionmentioning

confidence: 99%

“…Imidazolate-bridged binuclear metal complexes like bovine superoxide dismutase [Cu(II)-Im-Zn(II)SOD] 16 are of much interest. Of late, synthesis and characterization of several imidazolate-bridged binuclear copper(II) complexes have been reported [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] . All these complexes exhibit antiferromagnetic spin-exchange interactions.…”

Section: Introductionmentioning

confidence: 99%

Synthetic, spectral and solution studies on imidazolate-bridged copper(II)-copper(II) and copper(II)-zinc(II) complexes

et al. 2001

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Synthesis, spectral and solution studies on 2-ethyl imidazolate-bridged (2-EtIm) homo-binuclear copper(II)-copper(II) and hetero-binuclear copper(II)zinc(II) homologue are described. Magnetic moment values of homo-binuclear complexes indicate that the imidazolate group can mediate antiferromagnetic interactions. Optical spectra of hetero-binuclear complex at varying pH values suggest that the imidazolate-bridged complex is stable over the pH-range 7⋅15-10⋅0.

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ChemInform Abstract: Formation and Scission of the Imidazolate Bridge Linkage in Binuclear Copper(II) Complex with Glycylglycine as a Function of pH in Aqueous Solution.

et al. 1987

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283ChemInform Abstract The formation and scission of the imidazolate-bridge linkage in the binuclear Cu(II) complex (I) are studied in aqueous solutions as a function of pH. Potentiometric titration and ESR spectroscopy show that the binuclear complex (I) is formed in the range 9.8 < pH < 11.5. The bridge is broken by protonation at pH < 9.8 to give rise to the neutral mononuclear complexes (IIIa) and (IIIb). Above pH 11.5, the bridge in (I) is broken by OH ion to give rise to the ionic mononuclear complexes (IIa) and (IIb). The coordinated midazolate in (IIb) is not displaced by OH ion even under conditions of high pH. Equilibrium constants are determined.

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Formation and scission of the imidazolate-bridge linkage in binuclear copper(II) complex with glycylglycine as a function of pH in aqueous solution

Cited by 11 publications

References 23 publications

Pro-Oxidant Copper-Binding Mode of the Apo Form of ALS-Linked SOD1 Mutant H43R Denatured at Physiological Temperature

Pro-Oxidant Copper-Binding Mode of the Apo Form of ALS-Linked SOD1 Mutant H43R Denatured at Physiological Temperature

Synthetic, spectral and solution studies on imidazolate-bridged copper(II)-copper(II) and copper(II)-zinc(II) complexes

ChemInform Abstract: Formation and Scission of the Imidazolate Bridge Linkage in Binuclear Copper(II) Complex with Glycylglycine as a Function of pH in Aqueous Solution.

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