The mechanism of ascorbic acid oxidation by Cu(II)-poly-4-vinylpyridine complexes

Skurlatov, Yu. I.; Kovner, V.Ya.; Travin, S. O.; Kirsh, Yu. E.; Purmal, A. P.; Kabanov, V.Ya.

doi:10.1016/0014-3057(79)90036-3

Cited by 15 publications

(6 citation statements)

References 8 publications

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“…Depending on the ligands coordinating the Cu(II) center, the kinetics and mechanisms of the AA oxidation vary significantly. For example, when Cu(II) is coordinated by poly-4-vinylpyridine, its catalytic activity toward the AA oxidation increases by four orders of magnitude 42. The copper(II)-catalyzed AA oxidation, in the presence or absence of strong ligands, is generally believed to proceed by an alternating reduction-oxidation mechanism with the formation of an intermediate of cuprous (Cu(I)) species 42,43.…”

Section: Introductionmentioning

confidence: 99%

“…For example, when Cu(II) is coordinated by poly-4-vinylpyridine, its catalytic activity toward the AA oxidation increases by four orders of magnitude 42. The copper(II)-catalyzed AA oxidation, in the presence or absence of strong ligands, is generally believed to proceed by an alternating reduction-oxidation mechanism with the formation of an intermediate of cuprous (Cu(I)) species 42,43. Nonetheless, AA oxidation catalyzed by histidine (His) ligated copper proceeds via a different mechanism in which a ternary complex of O 2 –(His-Cu)–AA is formed 40.…”

Section: Introductionmentioning

confidence: 99%

“…The oxidation kinetics of AA has been extensively investigated by employing both free Cu(II) and Cu(II) complexes. − Depending on the ligands coordinating the Cu(II) center, the kinetics and mechanisms of the AA oxidation vary significantly. For example, when Cu(II) is coordinated by poly(4-vinylpyridine), its catalytic activity toward the AA oxidation increases by 4 orders of magnitude . The copper(II)-catalyzed AA oxidation, in the presence or absence of strong ligands, is generally believed to proceed by an alternating reduction−oxidation mechanism with the formation of an intermediate of cuprous (Cu(I)) species. , Nonetheless, AA oxidation catalyzed by histidine (His) ligated copper proceeds via a different mechanism in which a ternary complex of O 2 −(His−Cu)−AA is formed .…”

Section: Introductionmentioning

confidence: 99%

“…For example, when Cu(II) is coordinated by poly(4-vinylpyridine), its catalytic activity toward the AA oxidation increases by 4 orders of magnitude . The copper(II)-catalyzed AA oxidation, in the presence or absence of strong ligands, is generally believed to proceed by an alternating reduction−oxidation mechanism with the formation of an intermediate of cuprous (Cu(I)) species. , Nonetheless, AA oxidation catalyzed by histidine (His) ligated copper proceeds via a different mechanism in which a ternary complex of O 2 −(His−Cu)−AA is formed . Furthermore, although in the presence of an electron donor and Aβ−Cu(II) H 2 O 2 has been detected and the reaction has been proposed to proceed along the pathway outlined by reactions −, it is not clear if H 2 O 2 is the exclusive product or if other ROS are also generated.…”

Section: Introductionmentioning

confidence: 99%

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Reaction Rates and Mechanism of the Ascorbic Acid Oxidation by Molecular Oxygen Facilitated by Cu(II)-Containing Amyloid-β Complexes and Aggregates

Jiang

Liu

et al. 2010

J. Phys. Chem. B

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A forefront of the research on Alzheimer's disease (AD) is the interaction of amyloid beta (Aβ) peptides with redox metal ions (e.g., Cu(II), Fe(III) and Fe(II)) and the biological relevance of the Aβ-metal complexes to neuronal cell loss and homeostasis of essential metals and other cellular species. This work is concerned with the kinetic and mechanistic studies of the ascorbic acid oxidation reaction by molecular oxygen that is facilitated by Cu(II) complexes with Aβ(1-16), Aβ(1-42), and aggregates of Aβ(1-42). The reaction rate was found to linearly increase with the concentrations of Aβ-Cu(II) and dissolved oxygen, and be invariant with high ascorbic acid concentrations. The rate constants were measured to be 117.2 ± 15.4 and 15.8 ± 2.8 M −1 s −1 at low (<100 µM) and high AA concentrations, respectively. Unlike free Cu(II), in the presence of AA, Aβ-Cu(II) complexes facilitate the reduction of oxygen by producing H 2 O 2 as a major product. Such a conclusion is drawn on the basis that the reaction stoichiometry between AA and O 2 is 1:1 when Aβ concentration is kept at a much greater value than that of Cu(II). A mechanism is proposed for the AA oxidation in which the oxidation states of the copper center in the Aβ complex alternates between 2+ and 1+. The catalytic activity of Cu(II) towards O 2 reduction was found to decrease in the order of free Cu(II) > Aβ(1-16)-Cu(II) > Aβ(1-42)-Cu(II) > Cu(II) complexed by the Aβ oligomer/fibril mixture > Cu(II) in Aβ fibrils. The finding that Cu(II) in oligomeric and fibrous Aβ aggregates possesses considerable activity towards H 2 O 2 generation is particularly significant, since in senile plaques of AD patients the co-existing copper and Aβ aggregates have been suggested to inflict oxidative stress through the production of reactive oxygen species (ROS). Although Cu(II) bound to oligomeric and fibrous Aβ aggregates is less effective than free Cu(II) and the monomeric Aβ-Cu(II) complex in producing ROS, in vivo the Cu(II)-containing Aβ oligomers and fibrils might be more biologically relevant given their stronger association with cell membranes and the closer proximity of ROS to cell membranes.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Reaction Rates and Mechanism of the Ascorbic Acid Oxidation by Molecular Oxygen Facilitated by Cu(II)-Containing Amyloid-β Complexes and Aggregates

Jiang

Liu

et al. 2010

J. Phys. Chem. B

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“…We demonstrated the oxidation by the Cu(II) ion‐accumulated RNA‐SiNSi hybrid material (Cu‐RNA‐SiNSi material). Generally, ascorbic acid is oxidized by Cu(II) ions and produces dehydroascorbic acid . Therefore, we measured the oxidation of ascorbic acid by the Cu‐RNA‐SiNSi material.…”

Section: Resultsmentioning

confidence: 99%

Preparation of water‐insoluble and biochemically stable RNA hybrid material

Yamada

Tohyama

Yamada

2018

Polymers for Advanced Techs

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RNA, which plays an important role in the transcription and translation of genetic processes, has novel functional material abilities, such as the complementary interaction with nucleic acid bases, intercalation, and the binding with metal ions. However, because the RNA is a water-soluble and biochemically unstable biopolymer, RNA cannot be used as a polymer material. Therefore, we prepared a water-insoluble RNA-inorganic hybrid material by mixing the RNA and a silane coupling reagent, bis(3-trimethoxysilylpropyl)amine. The RNA-inorganic hybrid material did not show complete hydrolysis in spite of the incubation with the RNA hydrolysis enzyme Ribonuclease A for 72 hours. In addition, RNA-inorganic composite material effectively accumulated various metal ions, such as heavy and rare-earth metal ions. Furthermore, when the Cu(II) ion-accumulated RNA-inorganic hybrid material was incubated in an aqueous ascorbic acid solution, dehydroascorbic acid was produced by the oxidative effect of Cu(II) ions in RNA-inorganic hybrid material. KEYWORDS environmental material, metal ion, organic-inorganic hybrid material, RNA, three-dimensional network

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Enzyme-Mimetic Polymers

Imanishi

1985

Bioactive Polymeric Systems

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The mechanism of ascorbic acid oxidation by Cu(II)-poly-4-vinylpyridine complexes

Cited by 15 publications

References 8 publications

Reaction Rates and Mechanism of the Ascorbic Acid Oxidation by Molecular Oxygen Facilitated by Cu(II)-Containing Amyloid-β Complexes and Aggregates

Reaction Rates and Mechanism of the Ascorbic Acid Oxidation by Molecular Oxygen Facilitated by Cu(II)-Containing Amyloid-β Complexes and Aggregates

Preparation of water‐insoluble and biochemically stable RNA hybrid material

Enzyme-Mimetic Polymers

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