XANES study of iron displacement in the haem of myoglobin

Bianconi, A.; Congiu‐Castellano, A.; Dell’Ariccia, M.; Giovannelli, Alessandro; Durham, P. J.; Burattini, E.; Barteri, Mario

doi:10.1016/0014-5793(84)81263-6

Cited by 29 publications

(17 citation statements)

References 18 publications

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“…Lineshape of XANES spectra exhibit a structure due to the existence of different peaks distributed along the K-absorption edge. Energy positions and relative intensities of these peaks are correlated with the atomic arrangements of each hemoglobin derivative (18). Thus, comparison between the position of the K-absorption edge of different hemoglobin derivatives is not sufficiently significant.…”

Section: Resultsmentioning

confidence: 99%

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

Pin¹,

Valat²,

Cortès³

et al. 1985

Biophysical Journal

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K-absorption edge of coordinated ions exhibits a fine structure (through the use of XANES, or x-ray absorption near edge structures) that reflects the electronic repartition and the chemical reactivity of these ions. Comparative analysis of iron K-absorption-edge shape for hemoglobin derivatives with different ligand affinity suggests strongly that in hemoglobin, iron-forms with high and low affinity are highly improbable.

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Section: Resultsmentioning

confidence: 99%

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

Pin¹,

Valat²,

Cortès³

et al. 1985

Biophysical Journal

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“…Neither of these two possibilites supports the conclusion of Guiles et al (1990b) that no oxidation of the Mn cluster took place in this step. For the former to be the case, the ligand must be bound to a special site of the Mn(III) ion such as the 6th coordination site of a haem iron, to which the K-edge is known to be very sensitive (Bianconi 1984). Indeed, the Mn cluster in the S 2 state is considered to contain only one Mn(III) ion in a di-#-oxo bridged Mn(III,IV) dimeric subunit (Kusunoki 1992a) whose di-#-oxo bridge plane can play the same role as the haem plane in the excitation spectrum of a photo-electron near K-edge.…”

Section: [D+si]l = Cg[d+si]o + (1-a-]3)[d+si_l]omentioning

confidence: 99%

Manganese K-edge X-ray absorption spectra of the cyclic S-states in the photosynthetic oxygen-evolving system

et al. 1993

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A set of Mn K-edge XANES spectra due to the redox states S0-S3 of the OEC were determined by constructing a highly-sensitive X-ray detection system for use with physiologically native PS II membranes capable of cycling under a series of saturating laser-flashes. The spectra showed almost parallel upshifts with relatively high K-edge half-height energies given by 6550.9±0.2 eV, 6551.7±0.2 eV, 6552.5±0.2 eV and 6553.6±0.2 eV for the S0, S1, S2 and S3 states, respectively. The successive difference spectra between S0 and S1, S1 and S2, and S2 and S3 states were found to exhibit a similar peak around 6552-6553 eV, indicating that one Mn(III) ion or its direct ligand is univalently oxidized upon each individual S-state transition from S0 to S3. The present data, together with other observations of EPR and pre-edge XANES spectroscopy, suggest that the oxidation state of the Mn cluster undergoes a periodic change; S0: Mn(III,III,III,IV) → S1: Mn(III,IV,III,IV) → S2: Mn(III,IV,IV,IV) → S3: Mn(IV,IV,IV,IV) or Mn(III,IV,IV,IV)·L(+) with L being a direct ligand of a Mn(III) ion.

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“…XAS is a powerful method that used to generate unique structural and electronic details of the heme pocket. The XAS spectrum of a metalloprotein provides information about metal oxidation state, metal spin state, the number and type of ligands bound to the metal, and metal-ligand bond lengths; as such, XAS has been widely used to examine the solution-state structure of metal centers in numerous metalloproteins [19–24]. The position of the X-ray absorption iron K-edge, which represents the excitation energy of the core shell electron, is determined by the maximum of the first derivative spectrum.…”

Section: Introductionmentioning

confidence: 99%

Probing the local electronic and geometric properties of the heme iron center in a H-NOX domain

Dai

Boon

2011

Journal of Inorganic Biochemistry

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Heme-Nitric oxide and/or OXygen binding (H-NOX) proteins are a family of diatomic gas binding hemoproteins that have attracted intense research interest. Here we employ X-ray absorption near-edge structure (XANES) spectroscopy to study the nitric oxide (NO) binding site of H-NOX. This is the first time this technique has been utilized to examine the NO/H-NOX signaling pathway. XANES spectra of wildtype and a point mutant (proline 115 to alanine, P115A) of the H-NOX domain from Thermoanaerobacter tengcongensis (Tt H-NOX) were obtained and analyzed for ferrous and ferric complexes of the protein. This work provides specific structural characterization of the solution state of several Tt H-NOX ferrous complexes (-unligated, -NO, and -CO) that were previously unavailable. Our iron K-edges indicate effective charge on the iron center in the various complexes and report on the electronic environment of heme iron. We analyzed the ligand field indicator ratio (LFIR), which is extracted from XANES spectra, for each complex, providing an understanding of ligand field strength, spin state of the central iron, movement of the iron atom upon ligation, and ligand binding properties. In particular, our LFIRs indicate that the heme iron is dramatically displaced towards the distal pocket during ligand binding. Based on these results, we propose that iron displacement towards the distal heme pocket is an essential step in signal initiation in H-NOX proteins. This provides a mechanistic link between ligand binding and the changes in heme and protein conformation that have been observed for H-NOX family members during signaling.

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XANES study of iron displacement in the haem of myoglobin

Cited by 29 publications

References 18 publications

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

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

Manganese K-edge X-ray absorption spectra of the cyclic S-states in the photosynthetic oxygen-evolving system

Probing the local electronic and geometric properties of the heme iron center in a H-NOX domain

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