Mechanism of catalase activity in aqueous solutions of dimanganese(III,IV) ethylenediamine-N,N prime -diacetate
Journal Article
·
· Inorganic Chemistry; (USA)
- Louisiana State Univ., Baton Rouge (USA)
Manganous ions, ligated by ethylenediamine-N,N{prime}-diacetate (edda = L) decompose hydrogen peroxide with a rate law {minus}d(H{sub 2}O{sub 2})/dt = k{sub 17}(Mn(edda))(H{sub 2}O{sub 2}) where k{sub 17} = 5.4 M{sup {minus}1} s{sup {minus}1} at pH 7. The reduction of peroxide to water is initiated by the reaction of Mn{sup II}L with a dinuclear Mn{sup III,IV}L{sub 2}. A subsequent fast reaction between the transient product of this reaction and hydrogen peroxide or tert-butyl hydroperoxide effectively oxidizes Mn(II) to Mn(IV) in a concerted step without formation of the hydroxyl radical. The green mixed-valence complex, which is probably a bis({mu}-oxo)-bridged structure, is stable in neutral aqueous solution and exhibits a 16-line ESR signal in frozen solution. The basis of catalase activity is the autocatalytic formation of this complex when hydrogen peroxide is reduced by manganese(II). The catalase cycle is independent of the formation of oxy radicals. Mononuclear Mn{sup III}edda and Mn{sup II}edda react with superoxide radicals, but the decomposition of peroxide is virtually independent of these reactions. In unbuffered solutions, with a moderate excess of hydrogen peroxide, an oscillation in the concentration of the dinuclear complex is detected. 28 refs., 10 figs., 5 tabs.
- OSTI ID:
- 6956688
- Journal Information:
- Inorganic Chemistry; (USA), Journal Name: Inorganic Chemistry; (USA) Vol. 29:5; ISSN 0020-1669; ISSN INOCA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
10 SYNTHETIC FUELS
100300* -- Synthetic Fuels-- Properties & Composition-- (1990-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
AMINO ACIDS
AQUEOUS SOLUTIONS
CARBOXYLIC ACIDS
CATALASE
CHELATING AGENTS
CHEMICAL REACTIONS
DATA
DISPERSIONS
EDTA
ENZYMES
EXPERIMENTAL DATA
HYDROGEN COMPOUNDS
HYDROGEN PEROXIDE
INFORMATION
MANGANESE COMPOUNDS
MIXTURES
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDOREDUCTASES
OXYGEN COMPOUNDS
PEROXIDASES
PEROXIDES
REDUCTION
SOLUTIONS
TRANSITION ELEMENT COMPOUNDS
100300* -- Synthetic Fuels-- Properties & Composition-- (1990-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
AMINO ACIDS
AQUEOUS SOLUTIONS
CARBOXYLIC ACIDS
CATALASE
CHELATING AGENTS
CHEMICAL REACTIONS
DATA
DISPERSIONS
EDTA
ENZYMES
EXPERIMENTAL DATA
HYDROGEN COMPOUNDS
HYDROGEN PEROXIDE
INFORMATION
MANGANESE COMPOUNDS
MIXTURES
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDOREDUCTASES
OXYGEN COMPOUNDS
PEROXIDASES
PEROXIDES
REDUCTION
SOLUTIONS
TRANSITION ELEMENT COMPOUNDS