On the influence of allosteric effectors on the electron paramagnetic spectrum of nitric oxide hemoglobin

Rein, H.; Ristau, O.; Scheler, W

doi:10.1016/0014-5793(72)80817-2

Cited by 114 publications

(43 citation statements)

References 13 publications

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“…Thus oxygen is more effective in displacing the equilibrium towards the R structure than NO. The change in the quaternary structure is clearly detected by the EPR spectrum of nitric oxide [5][6][7][8][9][10]. In the T structure the strong trans-effect of NO can disrupt the proximal histidine iron bond of a-chains giving rise to a well-resolved 3-line hyperfine spectrum [13,14].…”

Section: Published By Elsevier Biomedical Pressmentioning

confidence: 99%

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Turtle hemoglobin: evidence of a T‐state oxyhemoglobin

Louro

Bemski

1982

FEBS Letters

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Section: Published By Elsevier Biomedical Pressmentioning

confidence: 99%

“…Nitric oxide derivatives were studied. Nitric oxide binds to hemes and is known to be a label sensitive to the quaternary structure of hemoglobin [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Turtle hemoglobin: evidence of a T‐state oxyhemoglobin

Louro

Bemski

1982

FEBS Letters

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“…The quaternary state of nitrosyl hemoglobin has been investigated using combinations of absorption, electron paramagnetic resonance (EPR), and nuclear magnetic resonance (NMR) spectroscopies (15)(16)(17)(18)(19)(20). The quaternary state of tetranitrosyl hemoglobin favors the R-state when it is stripped of organic phosphates such as 2,3-diphosphoglycerate (DPG) but favors the T-state in the presence of IHP (18,21).…”

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confidence: 99%

Effects of Iron Nitrosylation on Sickle Cell Hemoglobin Solubility

Lockamy

Chen

et al. 2002

Journal of Biological Chemistry

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One mechanism by which nitric oxide (NO) has been proposed to benefit patients with sickle cell disease is by reducing intracellular polymerization of sickle hemoglobin (HbS). In this study we have examined the ability of nitric oxide to inhibit polymerization by measuring the solubilizing effect of iron nitrosyl sickle hemoglobin (HbS-NO). Electron paramagnetic resonance spectroscopy was used to confirm that, as found in vivo, the primary type of NO ligation produced in our partially saturated NO samples is pentacoordinate ␣-nitrosyl. Linear dichroism spectroscopy and delay time measurements were used to confirm polymerization. Based on sedimentation studies we found that, although fully ligated (100% tetranitrosyl) HbS is very soluble, the physiologically relevant, partially ligated species do not provide a significant solubilizing effect. The average solubilizing effect of 26% NO saturation was 0.045; much less than the 0.15 calculated for the effect of 26% oxygen saturation. Given the small amounts of NO-ligated hemoglobin achievable through any kind of NO therapy, we conclude that NO therapy does not benefit patients through any direct solubilizing effect.Sickle cell disease is caused by a mutation in the sixth codon of the ␤-globin gene that results in the hydrophobic residue valine replacing hydrophilic glutamate in the hemoglobin (Hb)

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“…The second reason is that, in contrast to oxyhemoglobin and carbonmonoxyhemoglobin, NO-Hb shows a pronounced R-to-T transition (12,13) in the presence of inositol hexaphosphate, this transition being also rather sensitive to changes (5,9,10) in pH of the surrounding environment. One of the properties of NO-Hb that is a sensitive indicator of changes of structure under the influence of inositol hexaphosphate or changes in pH is the splitting produced (3)(4)(5)(6)(7)(8)(9)(10) in EPR spectra by 14N hyperfine interactions. Thus, in NO-Hb A, in the presence of inositol hexaphosphate or at low pH one finds for the aY chain a 3-line hyperfine pattern associated with the hyperfine interaction of the '4N nucleus of NO.…”

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confidence: 99%

“…First, it is a six-liganded hemoglobin derivative that is paramagnetic with spin 1/2, which makes it amenable for electron paramagnetic resonance (EPR) studies (2)(3)(4)(5)(6)(7)(8)(9)(10). Such studies allow one to follow the changes in the electron distribution over the molecule associated with transitions between R and T states, considered to be of crucial importance in the explanation of cooperativity (11) in the oxygen-binding properties of hemoglobin.…”

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confidence: 99%

Origin of observed changes in ¹⁴ N hyperfine interaction accompanying R → T transition in nitrosylhemoglobin

Mun

Chang

Das

1979

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

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Theoretical investigations of electronic distributions in eight different structural forms of nitrosylhemoglobin were carried out to study the changes in 14N hyperfine interaction observed with the transition from R to T structures under the influence of inositol hexaphosphate or changing pH. Four of the eight forms studied consisted of protonated and deprotonated N ros in the proximal imidazole ligand with linear and bent Fe-N-0 structures. Two other forms had a straight Fe-N-O structure and Fe-Im bond stretched by 0.5 and 1.0 .A. The other two systems we have studied are five-liganded NO-heme with bent and straight Fe-N-O structures. Our investigations show that arrangements of energy levels did not differ significantly among all the structures, the unpaired electron always occupying an antibonding orbital with d.2 symmetry. The protonated and deprotonated systems with either linear or bent Fe-N-O structure showed substantial hyperfine interaction of the 14N nuclei of the NO group and the Nf atom of the proximal imidazole, indicating that a 9-line electron spin resonance hyperfine pattern (R structure) would be expected in all four cases. On the other hand, the extensions of the Fe-Im bond produce a sizeable decrease in the 14Nf hyperfine interaction, indicating that an extension beyond 1.0 A\ would provide a 3-line hyperfine pattern close to that found for the five-liganded NO-heme system. Our results thus provide quantitative support for the model of severe extension or cleavage of the Fe-N, bond proposed in the literature for explaining the R-to-T transition of the a-chain of nitrosylhemoglobin.The study of the properties of nitrosylhemoglobin (NO-Hb) has assumed major importance (1-4) in recent years for two main reasons. First, it is a six-liganded hemoglobin derivative that is paramagnetic with spin 1/2, which makes it amenable for electron paramagnetic resonance (EPR) studies (2-10). Such studies allow one to follow the changes in the electron distribution over the molecule associated with transitions between R and T states, considered to be of crucial importance in the explanation of cooperativity (11) in the oxygen-binding properties of hemoglobin. The second reason is that, in contrast to oxyhemoglobin and carbonmonoxyhemoglobin, NO-Hb shows a pronounced R-to-T transition (12,13) in the presence of inositol hexaphosphate, this transition being also rather sensitive to changes (5, 9, 10) in pH of the surrounding environment. One of the properties of NO-Hb that is a sensitive indicator of changes of structure under the influence of inositol hexaphosphate or changes in pH is the splitting produced (3-10) in EPR spectra by 14N hyperfine interactions. Thus, in NO-Hb A, in the presence of inositol hexaphosphate or at low pH one finds for the aY chain a 3-line hyperfine pattern associated with the hyperfine interaction of the '4N nucleus of NO. On increasing the pH beyond 8.0, even in the presence of inositol hexaphosphate one sees a change (5) from the 3-line to a 9-line pattern, indicating that th...

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On the influence of allosteric effectors on the electron paramagnetic spectrum of nitric oxide hemoglobin

Cited by 114 publications

References 13 publications

Turtle hemoglobin: evidence of a T‐state oxyhemoglobin

Turtle hemoglobin: evidence of a T‐state oxyhemoglobin

Effects of Iron Nitrosylation on Sickle Cell Hemoglobin Solubility

Origin of observed changes in ¹⁴ N hyperfine interaction accompanying R → T transition in nitrosylhemoglobin

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On the influence of allosteric effectors on the electron paramagnetic spectrum of nitric oxide hemoglobin

Cited by 114 publications

References 13 publications

Turtle hemoglobin: evidence of a T‐state oxyhemoglobin

Turtle hemoglobin: evidence of a T‐state oxyhemoglobin

Effects of Iron Nitrosylation on Sickle Cell Hemoglobin Solubility

Origin of observed changes in 14 N hyperfine interaction accompanying R → T transition in nitrosylhemoglobin

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Origin of observed changes in ¹⁴ N hyperfine interaction accompanying R → T transition in nitrosylhemoglobin