Ligand binding processes in hemoglobin. Chemical reactivity of iron studied by XANES spectroscopy

Pin, Serge; Valat, P.; Cortès, R.; Michalowicz, Alain; Alpert, Bernard

doi:10.1016/s0006-3495(85)83862-5

Cited by 20 publications

(5 citation statements)

References 27 publications

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“…The experimental XANES edge position, E 0 , is determined as the maximum of the first derivative of the spectrum, which is very sensitive to the oxidation state. The comparison between the first derivative of the XANES spectra of free oxyHb and deoxyHb in this work with those published by Wilson et al [ 26 ] or Pin et al [ 27 ] reveals the same spectral shape.…”

Section: Resultssupporting

confidence: 84%

“…However, our observations do not exclude other mechanisms. Large changes in affinity without modification of the iron electronic structure have indeed been identified in carp Hb [ 39 ] and in human Hb in the presence of the inositol hexaphosphate (IHP) heterotropic effector [ 27 ]. The affinity changes may also result in part from a decrease in protein fluctuations [ 40 ] following adsorption, which controls the O 2 diffusion process inside the protein matrix [ 41 ].…”

Section: Resultsmentioning

confidence: 99%

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How Nanoparticles Modify Adsorbed Proteins: Impact of Silica Nanoparticles on the Hemoglobin Active Site

Giraudon--Colas

Devineau

Marichal

et al. 2023

IJMS

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The adsorption of proteins on surfaces has been studied for a long time, but the relationship between the structural and functional properties of the adsorbed protein and the adsorption mechanism remains unclear. Using hemoglobin adsorbed on silica nanoparticles, we have previously shown that hemoglobin’s affinity towards oxygen increases with adsorption. Nevertheless, it was also shown that there were no significant changes in the quaternary and secondary structures. In order to understand the change in activity, we decided in this work to focus on the active sites of hemoglobin, the heme and its iron. After measuring adsorption isotherms of porcine hemoglobin on Ludox silica nanoparticles, we analyzed the structural modifications of adsorbed hemoglobin by X-ray absorption spectroscopy and circular dichroism spectra in the Soret region. It was found that upon adsorption, there were modifications in the heme pocket environment due to changes in the angles of the heme vinyl functions. These alterations can explain the greater affinity observed.

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Section: Resultssupporting

confidence: 84%

Section: Resultsmentioning

confidence: 99%

How Nanoparticles Modify Adsorbed Proteins: Impact of Silica Nanoparticles on the Hemoglobin Active Site

Giraudon--Colas

Devineau

Marichal

et al. 2023

IJMS

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“…The X-ray absorption iron K-edge reveals the electronic transitions from the 1 s level to the lowest unoccupied atomic states (Bianconi, 1980). The effects of different ligands binding to the heme iron atom can be characterized by comparative analyses of the K-edge shapes of heme proteins (Morante et al, 1983;Pin et al, 1985). A heme iron electronic reorganization, subsequent to spin redistribution, is observable to about 20 eV, corresponding to the principal peak(s) of the derivative of the XANES spectrum (Oyanagi et al, 1987;Pin et al, 1989).…”

Section: Resultsmentioning

confidence: 99%

The Heme Iron Coordination Complex in His64(E7)Tyr Recombinant Sperm Whale Myoglobin

Pin¹,

Alpert²,

Cortès³

et al. 1994

Biochemistry

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By using site-directed mutagenesis of recombinant sperm whale (SW) myoglobin, the native distal histidine residue, at position 64 (the helical position E7), has been replaced with a tyrosine. The mutation of His64Tyr SW myoglobin has an analogous heme iron electronic structure as that of native hemoglobins M Boston and M Saskatoon. Optical spectroscopy showed that the distal tyrosine bound to the heme iron had a pK value of 5.6. In the pH range of 4.7-11.0, electron spin resonance spectroscopy suggested the presence of two heme iron ligation schemes: the heme iron bound to a distal water molecule or to a distal tyrosine residue. The heme iron coordination in the wild-type myoglobin and in the His64Tyr SW Mb mutant was studied by X-ray absorption near-edge structure (XANES) spectroscopy. Indeed, the heme iron K-edge reflects the electronic organization of the metal inside the six-coordinated complex. Comparative analysis of X-ray absorption heme iron K-edge shapes showed that the heme iron of His64Tyr SW myoglobin is bound to the oxygen atom from the phenol group of the distal tyrosine residue (Fe-OH phi). When the pH value decreased from pH 7 to 5.6, the Fe-OH phi bond strength decreased, resulting in an increase of the heme iron high-spin population of His64Tyr SW myoglobin. At low pH values, the Fe-OH phi bond can be disrupted with the possibility of heme iron binding of another ligand having a higher affinity.(ABSTRACT TRUNCATED AT 250 WORDS)

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“…However, heme protein molecules in solution do not have the rigidity that they exhibit in the crystal form (Makinen et al, 1979;Kawamura-Konishi & Suzuki, 1988; El Antri et al, 1989a). Spectroscopic techniques such as circular dichroism (Sugita et al, 1971;El Antri et al, 1989b), infrared absorption of CO stretching vibration (Makinen et al, 1979; or X-ray absorption near-edge structure (XANES) of the iron (Durham et al, 1983;Pin et al, 1985;Bianconi et al, 1986;Amiconi et al, 1989) provide information on the structural and dynamic properties of the solubilized protein. Using these three techniques we have investigated the effects of two amides and two alcohols on the possible alterations of the heme (core deformation or heme tilt) as well as the iron-ligand bonding geometry.…”

mentioning

confidence: 99%

Alteration of heme axial ligands in hemoglobin by organic solvents analyzed by CD, FTIR and XANES techniques

Zentz¹,

Antri²,

Ma³

et al. 1991

Biochemistry

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The effects of mixed solvents on the ligand binding site in hemoglobin have been investigated though three spectroscopic techniques. Two classes of organic solvents (amides and alcohols) known to increase or decrease the hemoglobin affinity have been chosen for this study. The analysis of the iron CO stretching band shows that the ligand binding sites of alpha CO and beta CO subunits inside the alpha 2 beta 2 hemoglobin tetramer exhibit multiple conformations. From the circular dichroism and X-ray absorption near-edge structure data, it appears that no core deformation or heme reorientation occur with the affinity changes. The iron-ligand average bond angle is the sole parameter that depends on the external solvent. Since cosolvents seem to affect the dynamics rather than the hindrance of the heme cavity, we suggest that the protein affinity could be associated with a hierarchy of subtle dynamic states.

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Ligand binding processes in hemoglobin. Chemical reactivity of iron studied by XANES spectroscopy

Cited by 20 publications

References 27 publications

How Nanoparticles Modify Adsorbed Proteins: Impact of Silica Nanoparticles on the Hemoglobin Active Site

How Nanoparticles Modify Adsorbed Proteins: Impact of Silica Nanoparticles on the Hemoglobin Active Site

The Heme Iron Coordination Complex in His64(E7)Tyr Recombinant Sperm Whale Myoglobin

Alteration of heme axial ligands in hemoglobin by organic solvents analyzed by CD, FTIR and XANES techniques

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