Electron paramagnetic studies of nitric oxide haemoglobin derivatives: Isolated subunits and nitric oxide hybrids

Henry, Y.; Banerjee, R.

doi:10.1016/0022-2836(73)90094-6

Cited by 115 publications

(55 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In conventional first-derivative EPR displays, the met-Hb signals have an effectively f lat response in the region of the Fe(II)NO feature. The latter spectra were analyzed by using a deconvolution procedure (analogous to that used in the UV͞VIS spectroscopy), involving two components, corresponding to NO occupying alternatively ␤ or ␣ subunits (with 6-fold coordination) (15)(16)(17). Hyperfine structure suggestive of penta-coordination of the ␣ subunit Fe(II)NO hemes (15) was not observed in any EPR spectra.…”

Section: Methodsmentioning

confidence: 99%

Routes to S -nitroso-hemoglobin formation with heme redox and preferential reactivity in the β subunits

Luchsinger

Rich

Gow

et al. 2003

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

202

207

View full text Add to dashboard Cite

Previous studies of the interactions of NO with human hemoglobin have implied the predominance of reaction channels that alternatively eliminate NO by converting it to nitrate, or tightly complex it on the ␣ subunit ferrous hemes. Both channels could effectively quench NO bioactivity. More recent work has raised the idea that NO groups can efficiently transfer from the hemes to cysteine thiols within the ␤ subunit (cys␤-93) to form bioactive nitrosothiols. The regulation of NO function, through its chemical position in the hemoglobin, is supported by response to oxygen and to redox agents that modulate the molecular and electronic structure of the protein. In this article, we focus on reactions in which Fe(III) hemes could provide the oxidative requirements of this NO-group transfer chemistry. We report a detailed investigation of the reductive nitrosylation of human met-Hb, in which we demonstrate the production of S-nitroso (SNO)-Hb through a heme-Fe(III)NO intermediate. The production of SNO-Hb is strongly favored (over nitrite) when NO is gradually introduced in limited total quantities; in this situation, moreover, heme nitrosylation occurs primarily within the ␤ subunits of the hemoglobin tetramer. SNO-Hb can similarly be produced when Fe(II)NO hemes are subjected to mild oxidation. The reaction of deoxygenated hemoglobin with limited quantities of nitrite leads to the production of ␤ subunit Fe(II)NO hemes, with SNO-Hb produced on subsequent oxygenation. The common theme of these reactions is the effective coupling of heme-iron and NO redox chemistries. Collectively, they establish a connectivity between hemes and thiols in Hb, through which NO is readily dislodged from storage on the heme to form bioactive SNO-Hb.T he transfer of NO groups within human hemoglobin from hemes to cys(␤-93) thiols to form a bioactive nitrosothiol represents a novel intramolecular biochemistry that is both of fundamental interest and has considerable implications for understanding the physiological effects of NO in the regulation of vascular tension and blood f low. A requirement of this transfer, common to biological S-nitrosylation (1), is the redox activation of the NO group (2). In this article, we report the results of experiments that probe the idea that heme-iron valence change can support the oxidative requirements of NO-group transfer and thus efficiently lead to the production of S-nitroso (SNO)-Hb. As a model of the reaction between ferric hemes and NO, the reductive nitrosylation of human methemoglobin is examined in detail. Product distribution assays reveal that SNO-Hb is formed as a nitrosation product, which, moreover, is substantially favored over NO 2 Ϫ when NO is gradually introduced as a limiting reagent; furthermore, in this situation, heme nitrosylation occurs primarily within the ␤ subunits of the Hb tetramer. A kinetic analysis unambiguously reveals the intermediacy of heme-Fe(III)NO in this reaction. To extend our observations to reactions that could mimic this chemistry but do not require an accumula...

show abstract

Section: Methodsmentioning

confidence: 99%

Routes to S -nitroso-hemoglobin formation with heme redox and preferential reactivity in the β subunits

Luchsinger

Rich

Gow

et al. 2003

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

202

207

View full text Add to dashboard Cite

show abstract

“…The measurements were carried out at 5, 11, and 35 K. The microwave power and 100-kHz field modulation were 5 mW and 1 mT at 5 and 11 K, and 2.5 mW and 0.5 mT at 35 K, respectively. To estimate the signal intensities for Fe-NO species of the frozen powdery samples, the double integrations of those signals were compared with the corresponding ones of the g ϭ 4.0 signal from the non-heme Fe-NO species of soybean lipoxygenase (Sigma) (39,40) and the g ϳ 2 signal from the heme b-NO species of horse heart myoglobin (Sigma) (41), on the assumption that the iron center in the those enzymes is completely occupied with NO. The set of intensity standards were measured at the three different concentrations, and the linear relationship with the protein concentrations and the double integrations of those signals was observed.…”

Section: Methodsmentioning

confidence: 99%

NO Reduction by Nitric-oxide Reductase from Denitrifying Bacterium Pseudomonas aeruginosa

Kumita

Matsuura

Hino

et al. 2004

Journal of Biological Chemistry

View full text Add to dashboard Cite

Nitric-oxide reductase (NOR) of a denitrifying bacterium catalyzes NO reduction to N 2 O at the binuclear catalytic center consisting of high spin heme b 3 and non-heme Fe B . The structures of the reaction intermediates in the single turnover of the NO reduction by NOR from Pseudomonas aeruginosa were investigated using optical absorption and EPR spectroscopies combined with an originally designed freeze-quench device. In the EPR spectrum of the sample, in which the fully reduced NOR was mixed with an NO solution and quenched at 0.5 ms after the mixing, two characteristic signals for the ferrous Fe B -NO and the penta-coordinated ferrous heme b 3 -NO species were observed. The CO inhibition of its formation indicated that two NO molecules were simultaneously distributed into the two irons of the same binuclear center of the enzyme in this state. The time-and temperature-dependent EPR spectral changes indicated that the species that appeared at 0.5 ms is a transient reaction intermediate prior to the N 2 O formation, in good agreement with the so-called "trans" mechanism. It was also found that the final state of the enzyme in the single turnover cycle is the fully oxidized state, in which the -oxo-bridged ligand is absent between the two irons of its binuclear center, unlike the resting form of NOR as isolated. On the basis of these present findings, we propose a newly developed mechanism for the NO reduction reaction conducted by NOR. Nitric-oxide reductase (NOR)1 is a metal-containing enzyme involved in biological denitrification processes. The enzyme catalyzes the two-electron reduction of nitric oxide (NO) to nitrous oxide (N 2 O) according to Equation 1 (1-4). Since the NO reduction reaction involves the N-O bond cleavage and the N-N bond formation, it is chemically interesting to elucidate the molecular mechanism of the NO reduction catalyzed by the metal enzymes.

show abstract

“…␣(Fe-NO)␣(Fe)␤(Fe) 2 or ␣(Fe-NO) 2 ␤(Fe) 2 . Such compounds were readily identified by their EPR spectra with a set of sharp triplet 14 N hyperfine structures (A z ϭ 17 Gauss) around g z ϭ 2.009, which is derived from the 5-coordinate nitrosyl hemes in the ␣-subunits. When rats or mice had been exposed to doses of lipopolyscaccaride, tumor necrosis factor, nitroglycerin, nitrite, or NO (7)(8)(9)(10)(11)(12), their plasma concentration of NO was known to increase.…”

Section: When Deoxy Hemoglobin (Hb)mentioning

confidence: 99%

Electron Paramagnetic Resonance and Oxygen Binding Studies of α-Nitrosyl Hemoglobin

Yonetani

Tsuneshige

Zhou

et al. 1998

Journal of Biological Chemistry

134

110

View full text Add to dashboard Cite

␣-Nitrosyl hemoglobin, ␣(Fe-NO) 2 ␤(Fe) 2 , which is frequently observed upon reaction of deoxy hemoglobin with limited quantities of NO in vitro as well as in vivo, has been synthetically prepared, and its reaction with O 2 has been investigation by EPR and thermodynamic equilibrium measurements. ␣-Nitrosyl hemoglobin is relatively stable under aerobic conditions and undergoes reversible O 2 binding at the heme sites of its ␤-subunits. Its O 2 binding is coupled to the structural/functional transition between T-(low affinity extreme) and R-(high affinity) states. This transition is linked to the reversible cleavage of the heme Fe-proximal His bonds in the ␣(Fe-NO) subunits and is sensitive to allosteric effectors, such as protons, 2,3-biphosphoglycerate, and inositol hexaphosphate. In fact, ␣(Fe-NO) 2 ␤(Fe) 2 is exceptionally sensitive to protons, as it exhibits a highly enhanced Bohr effect. The total Bohr effect of ␣-nitrosyl hemoglobin is comparable to that of normal hemoglobin, despite the fact that the oxygenation process involves only two ligation steps. All of these structural and functional evidences have been further confirmed by examining the reactivity of the sulfhydryl group of the Cys ␤93 toward 4,4-dipyridyl disulfide of several ␣-nitrosyl hemoglobin derivatives over a wide pH range, as a probe for quaternary structure. Despite the halved O 2 -carrying capacity, ␣-nitrosyl hemoglobin is fully functional (cooperative and allosterically sensitive) and could represent a versatile low affinity O 2 carrier with improved features that could deliver O 2 to tissues effectively even after NO is sequestered at the heme sites of the ␣-subunits. It is concluded that the NO bound to the heme sites of the ␣-subunits of hemoglobin acts as a negative allosteric effector of Hb and thus might play a role in O 2 /CO 2 transport in the blood under physiological conditions.

show abstract

Electron paramagnetic studies of nitric oxide haemoglobin derivatives: Isolated subunits and nitric oxide hybrids

Cited by 115 publications

References 29 publications

Routes to S -nitroso-hemoglobin formation with heme redox and preferential reactivity in the β subunits

Routes to S -nitroso-hemoglobin formation with heme redox and preferential reactivity in the β subunits

NO Reduction by Nitric-oxide Reductase from Denitrifying Bacterium Pseudomonas aeruginosa

Electron Paramagnetic Resonance and Oxygen Binding Studies of α-Nitrosyl Hemoglobin

Contact Info

Product

Resources

About