S-Nitrosohemoglobin: A mechanism for its formation in conjunction with nitrite reduction by deoxyhemoglobin

Nagababu, Enika; Ramasamy, Somasundaram; Rifkind, Joseph M.

doi:10.1016/j.niox.2006.01.012

Cited by 81 publications

(101 citation statements)

References 56 publications

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“…These processes formally involve an Fe(III)NO intermediary. We and others (16,25,29), however, had not been able to identify the production of Fe(III)NO in reactions between Hb and nitrite, although Rifkind et al (23,25) have inferred its presence. Here we took an alternative approach to analysis of UV-Vis spectra that has enabled the detection of a minority species, identified as Fe(III)NO.…”

Section: Discussionmentioning

confidence: 78%

“…Recent work by us (16) and others (21)(22)(23) has shown that oxidized hemes [Fe(III)], particularly ␤-chain hemes, are competent for this redox activity. Thus, ␤Fe(III)NO meets both the oxidative and structural requirements for SNO-Hb production (7,16,23). In related studies, Pezacki et al (18,24) reported that ␤Fe(III)NO accumulates during deoxygenation of SNO-Hb.…”

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confidence: 99%

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An S -nitrosothiol (SNO) synthase function of hemoglobin that utilizes nitrite as a substrate

Angelo

Singel

Stamler³

2006

Proc. Natl. Acad. Sci. U.S.A.

215

218

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Red blood cells (RBCs) act as O2-responsive transducers of vasodilator and vasoconstrictor activity in lungs and tissues by regulating the availability of nitric oxide (NO). Vasodilation by RBCs is impaired in diseases characterized by hypoxemia. We have proposed that the extent to which RBCs constrict vs. dilate vessels is, at least partly, controlled by a partitioning between NO bound to heme iron and to Cys␤93 thiol of hemoglobin (Hb). Hemes sequester NO, whereas thiols deploy NO bioactivity. In recent work, we have suggested that specific micropopulations of NO-liganded Hb could support the chemistry of S-nitrosohemoglobin (SNO-Hb) formation. Here, by using nitrite as the source of NO, we demonstrate that a (T state) micropopulation of a heme-NO species, with spectral and chemical properties of Fe(III)NO, acts as a precursor to SNO-Hb formation, accompanying the allosteric transition of Hb to the R state. We also show that at physiological concentrations of nitrite and deoxyHb, a S-nitrosothiol precursor is formed within seconds and produces SNO-Hb in high yield upon its prompt exposure to O 2 or CO. Deoxygenation͞reoxygenation cycling of oxyHb in the presence of physiological amounts of nitrite also efficiently produces SNO-Hb. In contrast, high amounts of nitrite or delays in reoxygenation inhibit the production of SNO-Hb. Collectively, our data provide evidence for a physiological S-nitrosothiol synthase activity of tetrameric Hb that depends on NO-Hb micropopulations and suggest that dysfunction of this activity may contribute to the pathophysiology of cardiopulmonary and blood disorders.hypoxic vasodilation ͉ nitric oxide ͉ S-nitrosohemoglobin ͉ S-nitrosylation H istorically, red blood cells (RBCs) have been regarded as transporters of oxygen (O 2 ) and carbon dioxide (CO 2 ), with the uptake of one and release of the other being reciprocally related. With the advent of the field of nitric oxide (NO) biology, RBCs also were thought to be scavengers of NO that could effectively quench its bioactivity. Some years ago, we noted that this limited view was inconsistent with the role of hemoglobin (Hb) in O 2 delivery, as sequestration of NO by Hb would lead to constriction of blood vessels, and this vasoconstriction, in turn, would limit the supply of O 2 (1). We subsequently demonstrated that vasoconstriction by RBCs is seen only at relatively high partial pressures of O 2 (pO 2 ); at lower pO 2 s characteristic of tissues (5-20 mm Hg), RBCs dilate blood vessels (2, 3). Vasodilation (of aortic or pulmonary artery rings) by RBCs in bioassay is rapid, in keeping with the temporal requirements of arterial-venous transit (in seconds) (3, 4). Moreover, when infused into animals, RBCs increase blood flow and improve oxygenation, an indication that RBCs elicit vasodilation in both the systemic and pulmonary circulations (1, 4-6). Collectively, the observation of vasoconstriction by RBCs at higher pO 2 but graded vasodilation with increasing hypoxia appears to provide a mechanism for matching blood flow to metaboli...

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Section: Discussionmentioning

confidence: 78%

mentioning

confidence: 99%

An S -nitrosothiol (SNO) synthase function of hemoglobin that utilizes nitrite as a substrate

Angelo

Singel

Stamler³

2006

Proc. Natl. Acad. Sci. U.S.A.

215

218

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“…The allosteric quaternary conformational change of hemoglobin at low oxygen pressure destabilizes the ␤-93 nitrosylated thiol and results in the transfer of NO to membrane thiol groups facilitating the release of the NO to the plasma and the vasculature. However, the extremely low levels of SNO-Hb (11) found in human blood and its instability (12) as a result of intracellular reducing conditions within the RBCs do not support the SNO-Hb hypothesis as the major mechanism for NO transport (11)(12)(13).…”

mentioning

confidence: 94%

“…However, the mechanism by which the NO produced in the red cell by nitrite reduction is exported without being trapped or destroyed is still unclear. Recent studies by 13,19) have suggested that the trapping of NO by deoxyHb and/or oxyHb can be bypassed by the formation of a metastable intermediate(s) that retains the NO in a state that is not quenched by reacting with oxyHb or deoxyHb.In this report, we quantitate the two intermediate species that are formed during the reduction of nitrite by deoxyHb when an excess of hemoglobin is present. We also demonstrate that one of the intermediate species designated as "Hb(II)NO ϩ % Hb(III)NO" has properties of Hb(II)NO ϩ and Hb(III)NO, respectively.…”

mentioning

confidence: 99%

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confidence: 99%

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Quantification of Intermediates Formed during the Reduction of Nitrite by Deoxyhemoglobin

Salgado

Nagababu

Rifkind

2009

Journal of Biological Chemistry

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Nitric oxide (NO) plays a crucial role in human physiology by regulating vascular tone and blood flow. The short life-span of NO in blood requires a mechanism to retain NO bioactivity in the circulation. Recent studies have suggested a mechanism involving the reduction of nitrite back to NO by deoxyhemoglobin in RBCs. A role for RBCs in transporting NO must, however, bypass the scavenging of NO in RBCs by hemoglobin. To understand how the nitrite reaction can deliver bioactive NO to the vasculature, we have studied the intermediates formed during the reaction. A reliable measure of the total concentration of heme-associated nitrite/NO intermediates formed was provided by combining filtration to measure free nitrite by chemiluminescence and electron paramagnetic resonance to measure the final product Hb(II)NO. By modifying the chemiluminescence method used to detect NO, we have been able to identify two intermediates: 1) a heme-associated nitrite complex that is released as NO in acid solution in the presence of ascorbate and 2) an intermediate that releases NO at neutral pH in the presence of ferricyanide when reacted with an Fe(III) ligand like azide. This species designated as "Hb(II)NO ؉ % Hb(III)NO" has properties of both isomeric forms resulting in a slower NO dissociation rate and much higher stability than Hb(III)NO, but provides a potential source for bioactive NO, which can be released from the RBC. This detailed analysis of the nitrite reaction with deoxyHb provides important insights into the mechanism for nitrite induced vasodilation by RBCs.Nitric oxide (NO), also known as the endothelium-derived relaxing factor, is an important messenger molecule involved in the regulation of vascular tone and blood flow (1). The primary source for the synthesis of NO in the circulatory system involves endothelial nitric-oxide synthase (2). This enzyme requires oxygen for the synthesis of NO and is, therefore, less effective in the microcirculation where hypoxic vasodilation regulates the delivery of oxygen. Because nitric oxide has a lifetime in blood of Ͻ2 ms (3), a mechanism is required to allow for more distal and sustained effects of NO at the reduced oxygen pressures found in the microcirculation. Recent studies have suggested that the bioactivity of NO can be conserved in the blood by the uptake of NO and/or nitrite by red blood cells (RBCs) 2 and its interaction with hemoglobin (4 -7). However, any role for the red cell in transporting nitric oxide must be able to avoid the very efficient scavenging of nitric oxide by both oxyhemoglobin (oxyHb) and deoxyhemoglobin (deoxyHb) that destroy and trap NO, respectively, preventing a physiological role for RBC NO.In a series of studies, Stamler and co-workers (7-10) have hypothesized that NO can bypass this difficulty by being transferred to the ␤-93 thiol group of hemoglobin (Hb) forming S-nitrosylated hemoglobin (SNO-Hb) when partially heme nitrosylated hemoglobin (Hb(II)NO) is oxygenated. The allosteric quaternary conformational change of hemoglobin at low oxy...

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Electrokinetics of Nitrite to Ammonia Conversion in the Neutral Medium Over A Platinum Surface

Islam,

Shahriar,

Rahaman

et al. 2024

Chemistry An Asian Journal

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Polycrystalline Pt electrode was employed to selectively convert nitrite ions ([[EQUATION]]) into useful nitrogenous compound through electrochemical reduction reaction in neutral medium. According to adsorptive stripping analysis, the reduction process produced nitric oxide (NO) on the surface of Pt electrode. The spectroscopic test and gas chromatographic studies discovered the presence of ammonia (NH3) in the electrolyzed solution, suggesting the transformation of adsorbed NO into NH3 during the reverse scan. Scan rate dependent investigation was performed to elucidate kinetic information relating to this reaction on Pt surface. From Ep vs scan rate (υ) and jp vs υ (logarithmic plot), it was found that the conversion of [[EQUATION]] ion into NO is an irreversible reaction which relies on the diffusion of [[EQUATION]] ions to electrode surface. The Tafel analysis unveiled that the first electron transfer sets the overall reaction rate, having formal reduction potential, E0’ = −0.46 V and standard heterogeneous rate constant, k0 = [[EQUATION]] cm s−1. Reductive transfer coefficient (α) is another kinetics parameter, which was found to be approximate 0.77 from the difference between Ep and Ep/2 of the voltammograms obtained over scan rate range 0.005 V s−1 to 0.250 V s−1, indicating a stepwise process.

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S-Nitrosohemoglobin: A mechanism for its formation in conjunction with nitrite reduction by deoxyhemoglobin

Cited by 81 publications

References 56 publications

An S -nitrosothiol (SNO) synthase function of hemoglobin that utilizes nitrite as a substrate

An S -nitrosothiol (SNO) synthase function of hemoglobin that utilizes nitrite as a substrate

Quantification of Intermediates Formed during the Reduction of Nitrite by Deoxyhemoglobin

Electrokinetics of Nitrite to Ammonia Conversion in the Neutral Medium Over A Platinum Surface

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