Metmyoglobin and methemoglobin as efficient traps for nitrosyl hydride (nitroxyl) in neutral aqueous solution

Bazylinski, Dennis A.; Hollocher, Thomas C.

doi:10.1021/ja00312a031

Cited by 120 publications

(61 citation statements)

References 3 publications

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“…2). This suggests that a 1:1 complex of NO Ϫ :MetHb is formed and that the production of NO Ϫ from OONO Ϫ occurs in high yield, as observed previously in the decomposition of Angeli's salt into NO Ϫ trapped by MetHb (28).…”

Section: Discussionsupporting

confidence: 77%

“…As in the case of the peroxynitrite experiments above, the reactions were carried out stepwise in small batches of 200 l of 75 mM H 2 O 2 and 0.5 ml CCl 4 solution, as described above for the OONO Ϫ decomposition reactions. (28). The identification of HbNO generated in the decomposition of peroxynitrite was based on the comparison of these two bands with those obtained from the reaction of MetHb with Angeli's salt (Na 2 N 2 O 3 ).…”

Section: Estimation Of Singlet Oxygen Yields From Peroxynitrite Decommentioning

confidence: 99%

“…The identification of HbNO generated in the decomposition of peroxynitrite was based on the comparison of these two bands with those obtained from the reaction of MetHb with Angeli's salt (Na 2 N 2 O 3 ). Angeli's salt, under neutral or mildly alkaline conditions, decomposes via its monoanion, HN 2 O 3 Ϫ , to quantitatively generate NO Ϫ , and is known to efficiently convert MetHb to HbNO as the sole heme product (28).…”

Section: Estimation Of Singlet Oxygen Yields From Peroxynitrite Decommentioning

confidence: 99%

“…Therefore, our experiments were performed in a limited pH range of 7.0 to 7.2 (28). In this pH range, the effect of pH on the absorption spectra, particularly in the wavelength region of interest from 535 to 635 nm, is small (Fig.…”

Section: Trapping Of Nomentioning

confidence: 99%

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The decomposition of peroxynitrite to nitroxyl anion (NO-) and singlet oxygen in aqueous solution

Khan

Kovacic

Kolbanovskiy

et al. 2000

Proceedings of the National Academy of Sciences

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The mechanism of decomposition of peroxynitrite (OONO ؊ ) in aqueous sodium phosphate buffer solution at neutral pH was investigated. The OONO ؊ was synthesized by directly reacting nitric oxide with superoxide anion at pH 13. The hypothesis was explored that OONO ؊ , after protonation at pH 7.0 to HOONO, decomposes into 1 O2 and HNO according to a spin-conserved unimolecular mechanism. Small aliquots of the concentrated alkaline OONO ؊ solution were added to a buffer solution (final pH 7.0 -7.2), and the formation of 1 O2 and NO ؊ in high yields was observed. The 1 O2 generated was trapped as the transannular peroxide (DPAO2) of 9,10-diphenylanthracene (DPA) dissolved in carbon tetrachloride. The nitroxyl anion (NO ؊ ) formed from HNO (pKa 4.5) was trapped as nitrosylhemoglobin (HbNO) in an aqueous methemoglobin (MetHb) solution. In the presence of 25 mM sodium bicarbonate, which is known to accelerate the rate of decomposition of OONO ؊ , the amount of singlet oxygen trapped was reduced by a factor of Ϸ2 whereas the yield of trapping of NO ؊ by methemoglobin remained unaffected. Because NO3 ؊ is known to be the ultimate decomposition product of OONO ؊ , these results suggest that the nitrate anion is not formed by a direct isomerization of OONO ؊ , but by an indirect route originating from NO ؊ .nitrosylhemoglobin ͉ diphenylanthracene endoperoxide P eroxynitrite is a potent oxidant formed by the near diffusioncontrolled reaction of nitric oxide (NO ⅐ ) and superoxide ion (O 2 Ϫ ) (1). Both nitric oxide and superoxide are produced by activated macrophages (2, 3), neutrophils (4), and endothelial cells (5, 6). There is evidence that peroxynitrite is formed in significant concentrations in vivo (7-9) and may contribute to an increased risk for cancer (10), artherosclerosis (11), stroke (12), and other diseases (13). Peroxynitrite is a stable anion in alkaline solution (pKa of 6.8); however, once protonated, it decomposes rapidly with a half-life of less than 1 s at physiological pH at 37°C (14), generating reactive species that readily react with biomolecules such as lipids (15), amino acids (16), and DNA (17). Central to the question of the biochemistry of peroxynitrite is the mechanism of decomposition and the identity of the reactive species, a subject of intense research and controversy (18-21). Speculations about the decomposition mechanisms are largely based on kinetic and thermodynamic considerations (22). It has been shown that bicarbonate ion enhances the rate of disappearance of peroxynitrite, leading to the proposal of a nitrosoperoxycarbonate anion adduct, with a distinctly different chemistry from that of OONO Ϫ (19).We reported previously that the mere acidification of an aqueous peroxynitrite solution resulted in chemiluminescence at 1,270 nm characteristic of the deactivation of singlet oxygen (23). By comparing the intensity of this emission to that of 1 O 2 generated by the reaction of hydrogen peroxide (H 2 O 2 ) with hypochlorite anion (OCl Ϫ ), which is known to be stoichiometric (24), it was...

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Section: Discussionsupporting

confidence: 77%

Section: Estimation Of Singlet Oxygen Yields From Peroxynitrite Decommentioning

confidence: 99%

Section: Estimation Of Singlet Oxygen Yields From Peroxynitrite Decommentioning

confidence: 99%

Section: Trapping Of Nomentioning

confidence: 99%

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The decomposition of peroxynitrite to nitroxyl anion (NO-) and singlet oxygen in aqueous solution

Khan

Kovacic

Kolbanovskiy

et al. 2000

Proceedings of the National Academy of Sciences

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“…Another commonly employed strategy involves reaction of HNO with ferric heme-containing proteins such as metmyoglobin. 18 In the presence of HNO, ferric hemes undergo reductive nitrosylation, resulting in detectable shifts in the absorbance spectrum of the enzyme. This reaction provides a highly selective means of screening for HNO generation, but the resulting Fe II (NO) complex is unstable in aerobic conditions and readily undergoes reoxidation.…”

Section: Introductionmentioning

confidence: 99%

Xerogel Optical Sensor Films for Quantitative Detection of Nitroxyl

2008

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Xerogel films were synthesized via sol-gel chemistry to fabricate optical nitroxyl (HNO) sensors. Selective detection of HNO in solution was achieved by monitoring the rates of manganese(III) meso-tetrakis(4-sulfonatophenyl) porphyrinate (Mn III TPPS) reductive nitrosylation in the anaerobic interior of aminoalkoxysilane-derived xerogel films. Nitroxyl permeability in sensor films deposited in round-bottom 96-well plates was enhanced via incorporation of trimethoxysilylterminated poly(amidoamine-organosilicon) (PAMAMOS) dendrimers in the xerogel network. The selectivity of Mn III TPPS for HNO, the overall sensitivity, and the working dynamic range of the resulting sensors were characterized. The HNO-sensing microtitre plates were used to quantify pH-dependent HNO generation by the recently described HNO-donor sodium-1-(isopropylamino)diazene-1-ium-1,2-diolate (IPA/NO), and compare HNO-production efficiency between IPA/NO and Angeli's salt, a traditional HNO-donor.

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Mechanisms of HNO Reactions with Ferric Heme Proteins

Shi

Zhang

2018

Angewandte Chemie

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Many HNO-scavenging pathways exist to regulate its biological and pharmacological activities.S uch reactions often involve ferric heme proteins and form an important basis for HNO probe development. However,mechanisms of HNO reactions with ferric heme proteins are largely unknown. We performed acomputational investigation using metmyoglobin and catalase as representative ferric heme proteins with neutral and negatively charged axial ligands to provide the first detailed pathways. The results reproduced experimental barriers well with an average error of 0.11 kcal mol À1 .T he ratelimiting step was found to be dissociation of the resting ligand or HNO coordination when there is no resting ligand. Forboth heme proteins,i nc ontrast to the non-heme case,t he reductive nitrosylation step was found to be barrierless proton-coupled electron transfer,w hichp rovides the major thermodynamic driving force for the overall reaction. The origin of the difference in reactivity between metmyoglobin and catalase was also revealed.

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Metmyoglobin and methemoglobin as efficient traps for nitrosyl hydride (nitroxyl) in neutral aqueous solution

Cited by 120 publications

References 3 publications

The decomposition of peroxynitrite to nitroxyl anion (NO-) and singlet oxygen in aqueous solution

The decomposition of peroxynitrite to nitroxyl anion (NO-) and singlet oxygen in aqueous solution

Xerogel Optical Sensor Films for Quantitative Detection of Nitroxyl

Mechanisms of HNO Reactions with Ferric Heme Proteins

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