Manganese(III) Biliverdin IX Dimethyl Ester:  A Powerful Catalytic Scavenger of Superoxide Employing the Mn(III)/Mn(IV) Redox Couple

Spasojević, Ivan; Batinić‐Haberle, Ines; Stevens, Robert; Hambright, Peter; Thorpe, A. N.; Grodkowski, J.; Neta, P.; Fridovich, Irwin

doi:10.1021/ic0004986

Cited by 105 publications

(94 citation statements)

References 115 publications

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“…This indirect competition kinetic method is widely used and well validated. 13 The scatter of the rate (∆Abs/min) data was similar for all experiments (∼0.01 min -1 ). However, from Figure •-flux (1000 U/mL catalase, phosphate buffer, 25.0°C).…”

mentioning

confidence: 60%

Vitamin B₁₂ and Redox Homeostasis: Cob(II)alamin Reacts with Superoxide at Rates Approaching Superoxide Dismutase (SOD)

et al. 2009

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We report a kinetic study of the reaction between superoxide and an important intracellular form of vitamin B12, cob(II)alamin. Superoxide is implicated in the pathophysiology of many inflammatory diseases, whereas vitamin B12 derivatives are often beneficial in their treatment. We found that cob(II)alamin reacts with superoxide at rates approaching those of superoxide dismutase itself, suggesting a probable mechanism by which vitamin B12 protects against chronic inflammation and modulates redox homeostasis.

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mentioning

confidence: 60%

Vitamin B₁₂ and Redox Homeostasis: Cob(II)alamin Reacts with Superoxide at Rates Approaching Superoxide Dismutase (SOD)

et al. 2009

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“…We have previously compared the k cat determined by pulse radiolysis and with cyt c assay for several of our Mn porphyrins and MnCl 2 [27,32]. The k cat determined by both methods were the same, which justified using a convenient cyt c assay for testing our prospective SOD mimics.…”

Section: Superoxide Dismutase Activitymentioning

confidence: 97%

“…The catalytic rate constants for the O 2 •− disproportionation were determined by the cytochrome c (cyt c) assay [31,32]. We have previously compared the k cat determined by pulse radiolysis and with cyt c assay for several of our Mn porphyrins and MnCl 2 [27,32].…”

Section: Superoxide Dismutase Activitymentioning

confidence: 99%

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SOD-like activity of Mn(II) β-octabromo-meso-tetrakis(N-methylpyridinium-3-yl)porphyrin equals that of the enzyme itself

DeFreitas-Silva

Rebouças

Spasojević

et al. 2008

Archives of Biochemistry and Biophysics

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Mn porphyrins are among the most efficient SOD mimics with potency approaching that of SOD enzymes. The most potent ones, Mn(III) N-alkylpyridylporphyrins bear positive charges in a close proximity to the metal site, affording thermodynamic and kinetic facilitation for the reaction with negatively charged superoxide. The addition of electron-withdrawing bromines onto β-pyrrolic positions dramatically improves thermodynamic facilitation for the O 2 •− dismutation. We have previously characterized the para isomer, Mn II Br 8 TM-4-PyP 4+ [Mn(II) β-octabromo-meso-tetrakis (N-methylpyridinium-4-yl)porphyrin]. Herein we fully characterized its meta analogue, Mn II Br 8 TM-3-PyP 4+ with respect to uv/vis spectroscopy, electron spray mass spectrometry, electrochemistry, O 2 •− dismutation, metal-ligand stability, and the ability to protect SOD-deficient E. coli in comparison with its para analogue. The increased electron-deficiency of the metal center stabilizes Mn in its +2 oxidation state. The metal-centered Mn III /Mn II reduction potential, E ½ = + 468 mV vs NHE, is increased by 416 mV with respect to non-brominated analogue, Mn III TM-3-PyP 5+ and is only 12 mV less positive than for para isomer. Yet, the complex is significantly more stable towards the loss of metal than its para analogue. As expected, based on the structure-activity relationships, a large increase in E ½ results in exceptionally high catalytic rate constant for the O 2 •− dismutation, log k cat ≥ 8.85; 1.5-fold increase with respect to the para isomer. The IC 50 was calculated to be ≤ 3.7 nM. Manipulation of the electron-deficiency of a cationic porphyrin resulted, therefore, in the highest k cat ever reported for a metalloporphyrin, being essentially identical to the k cat of superoxide dismutases (log k cat = 8.84 -9.30). The positive kinetic salt effect points to the unexpected, unique and first time recorded behavior of Mn β-octabrominated porphyrins when compared to other Mn porphyrins studied thus far. When species of opposing charges react, the increase in ionic strength invariably results in the decreased rate constant; with brominated porphyrins the opposite was found to be true. The effect is 3.5 -fold greater with meta than with para isomer, which is discussed with respect to the closer proximity of the quaternary nitrogens of the meta isomer to the metal center than that of the para isomer. The potency of Mn II Br 8 TM-3-PyP 4+ was corroborated by in vivo studies, where 500 nM allows SOD-deficient E. coli to grow ≥ 60% of the growth of wild type; at concentrations ≥5 μM it exhibits toxicity. Our work shows that exceptionally high k cat for the O 2 •− disproportionation can be achieved not only with an N 5 -type *Corresponding authors: Ynara Marina Idemori, Ph. D., Departamento de Química, ICEx, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Pampulha, Belo Horizonte, MG, 31270-901, Brazil., Tel: +55-31-3499-5762, Fax: +55-31-3499-5700, e-mail: ynara@ufmg.br NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH...

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“…Fisher and colleagues 16 using O 2 -detection with NBT reported a value of k = 6 x 10 5 M -1 s -1 for the reaction of Mn(II) EDTA with O 2 -, while a more recent study could only place an upper bound for this reaction of k < 3 x 10 5 M -1 s -1 using spectrophotometry/stopped flow 1 . It is noted however that other studies have found no evidence for this reaction [17][18][19][20] .…”

Section: Reactions Of O 2 -With Mn(ii) Organic Complexesmentioning

confidence: 71%

Reactivity of Inorganic Mn and Mn Desferrioxamine B with O₂, O₂^–, and H₂O₂in Seawater

Wuttig¹,

Heller²,

Croot³

2013

Environ. Sci. Technol.

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S2 Supplementary Information:Cautionary Tales for comparing O 2 -decay rates: The published literature for the reactivity of Mn complexes with O 2 -is littered with apparently contradictory results, some of which is related to the choice of buffer and the detection system employed 1, 2 . Problems may also occur through other redox reactions involving probe compounds (e.g. oxidation of ferrocytochrome, reduction of nitroblue tetrazolium (NBT)). In our evaluation of the literature we also came across two other critical problems:(1) The frequent use of the piperazine ring containing Good's buffer 3 HEPES (4- Calculation of rate data for superoxide. The raw chemiluminescence signal for the reaction between MCLA and O 2 -recorded by the computer was processed using a specially designed Labview TM VI constructed for this purpose using standard kinetic fitting procedures to determine both the 1 st (k obs ) and 2 nd order (k 2 ) rates simultaneously. The photon counter has a base counting period of 10 ms, for the present work we used average counts of an integration time of 200 ms. Dark background counts for this detector were typically 60 -120 counts s − 1 . Apparent(

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Manganese(III) Biliverdin IX Dimethyl Ester: A Powerful Catalytic Scavenger of Superoxide Employing the Mn(III)/Mn(IV) Redox Couple

Cited by 105 publications

References 115 publications

Vitamin B₁₂ and Redox Homeostasis: Cob(II)alamin Reacts with Superoxide at Rates Approaching Superoxide Dismutase (SOD)

Vitamin B₁₂ and Redox Homeostasis: Cob(II)alamin Reacts with Superoxide at Rates Approaching Superoxide Dismutase (SOD)

SOD-like activity of Mn(II) β-octabromo-meso-tetrakis(N-methylpyridinium-3-yl)porphyrin equals that of the enzyme itself

Reactivity of Inorganic Mn and Mn Desferrioxamine B with O₂, O₂^–, and H₂O₂in Seawater

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Manganese(III) Biliverdin IX Dimethyl Ester: A Powerful Catalytic Scavenger of Superoxide Employing the Mn(III)/Mn(IV) Redox Couple

Cited by 105 publications

References 115 publications

Vitamin B12 and Redox Homeostasis: Cob(II)alamin Reacts with Superoxide at Rates Approaching Superoxide Dismutase (SOD)

Vitamin B12 and Redox Homeostasis: Cob(II)alamin Reacts with Superoxide at Rates Approaching Superoxide Dismutase (SOD)

SOD-like activity of Mn(II) β-octabromo-meso-tetrakis(N-methylpyridinium-3-yl)porphyrin equals that of the enzyme itself

Reactivity of Inorganic Mn and Mn Desferrioxamine B with O2, O2–, and H2O2in Seawater

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Vitamin B₁₂ and Redox Homeostasis: Cob(II)alamin Reacts with Superoxide at Rates Approaching Superoxide Dismutase (SOD)

Vitamin B₁₂ and Redox Homeostasis: Cob(II)alamin Reacts with Superoxide at Rates Approaching Superoxide Dismutase (SOD)

Reactivity of Inorganic Mn and Mn Desferrioxamine B with O₂, O₂^–, and H₂O₂in Seawater