Resonance Raman study of oxyhemerythrin and hydroxomethemerythrin.  Evidence for hydrogen bonding of ligands to the iron-oxygen-iron center

Shiemke, Andrew K.; Loehr, Thomas M.; Sanders-Loehr, Joann

doi:10.1021/ja00269a050

Cited by 115 publications

(100 citation statements)

References 4 publications

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“…However, upon excitation at 363.8 nm, two bands were observed around 500 cm-' for S. cumanense oxyHr as depicted in Figure 6. In the previous report by Shiemke et al (1986), a shoulder was recognizable at a higher frequency side of the strong 480-cm-l band and was assigned to Y F~~. The corresponding band is clearly resolved in Figure 6A for the 1 6 0 2 derivative.…”

Section: While S Cumanensementioning

confidence: 54%

“…It is clear that the YOO and ~~e -0~ RR bands are shifted to higher and lower frequencies, respectively, in D2O. The frequency shifts to opposite directions were previously noted for Phascolopsis gouldii Hr , and from it, the protonation of bound oxygen and its hydrogen bonding to the p-oxo-bridged oxygen were proposed (Shiemke et al, , 1986. This proposal was justified by the high-resolution X-ray crystallographic analysis (Holmes et al, 1991).…”

Section: While S Cumanensementioning

confidence: 63%

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Resonance Raman study on the active-site structure of a cooperative hemerythrin

Kaminaka¹,

Takizawa²,

Handa³

et al. 1992

Biochemistry

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Resonance Raman spectra were observed for the oxy and azidomet forms of a cooperative hemerythrin (Hr) isolated from Lingula unguis and a noncooperative Hr from Siphonosoma cumanense. The O-O stretching frequency of the oxy derivative of the L. unguis Hr was lower in the high-affinity form generated at pH 7.6 than in the low-affinity form generated at pH 6.2, while that of the S. cumanense Hr did not change at those two pH values. The Fe-O-Fe symmetric stretching mode of L. unguis azidomet-Hr exhibited a frequency shift between pH 7.6 and 6.2, while that of S. cumanense was not shifted. However, the corresponding band of the oxy form did not show a pH-dependent frequency change. Therefore, it is noted that the azidomet form is not a suitable model for studying a mechanism of cooperativity, contrary to the structural similarity between the oxy and azidomet forms. The Fe-O2 as well as Fe-N3 stretching frequencies were found to have no relation with the oxygen affinity. Upon exchange of solvent from H2O to D2O, the O-O and Fe-O2 stretching modes of L. unguis Hr were shifted to higher and lower frequencies, respectively, and their magnitudes were the same for the high- and low-affinity forms. The same frequency shifts were observed for S. cumanense Hr.(ABSTRACT TRUNCATED AT 250 WORDS)

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Section: While S Cumanensementioning

confidence: 54%

Section: While S Cumanensementioning

confidence: 63%

Resonance Raman study on the active-site structure of a cooperative hemerythrin

Kaminaka¹,

Takizawa²,

Handa³

et al. 1992

Biochemistry

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“…The results of this section, in particular Eqns (20) and (21), provide an operational justification of the extrapolation of low-temperature data to physiological temperature where the kinetic processes become exponential. The justification rests on the invariance of the rebinding-curve profile at temperature Tf < T < T,.…”

Section: Geminate Recombinations At Low Temperaturementioning

confidence: 91%

“…The postulated conformational changes are not expected to be detectable by kinetic absorption measurements and the assumption must await independent confirmation by other methods of investigation. Most of the recent work has been concerned with the structure of the active site using resonant Raman scattering, X-ray crystallography and extended X-ray absorption fine structure (EXAFS) [19,20,341. Several studies have been devoted to the atomic mobility in methemerythrin, in relation to its antigenicity [35 -381.…”

Section: Kinetic Scheme and Conformation Change Of Hemerythrin Upon Bmentioning

confidence: 99%

Viscosity‐dependent energy barriers and equilibrium conformational fluctuations in oxygen recombination with hemerythrin

Lavalette

Tétreau

1988

European Journal of Biochemistry

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The recombination kinetics of photo-dissociated oxyhemerythrin (Sipunculus nudus) have been investigated between 298 K and 90 K. Fast geminate recombinations compete with oxygen escape into the solvent, from which a subsequent slower bimolecular rebinding takes place. In phosphate buffer @H 7.7) at 278 K, the fast and slow processes are exponential and have comparable amplitudes. Whereas the oxygen escape rate rapidly decreases upon increasing the viscosity, the inward rate from the solvent is found to be independent of viscosity, up to about 50 CP (50 mPa . s). The data suggest that a Brownian-motion-driven displacement of one or several side-chain residues is implied in oxygen escape from within the protein and also that hemerythrin undergoes a conformational change in the deoxy state.At higher viscosities and lower temperature only the geminate phase is observed and the kinetics progressively depart from an exponential. Below about 130 K, the kinetics resemble those reported in the literature for heme proteins. They are consistent with a temperature-independent non-equilibrium frozen distribution of conformational substates. However, between 190 K and 130 K, the profile of the kinetics is invariant on a log/ log plot and the results simply differ by a translation along the log t axis. It is shown that this property is expected only for a temperature-dependent distribution of substates in a Boltzmann equilibrium. From room temperature, where rebinding is exponential, down to the 'freezing' temperature, the geminate recombinations display a variety of kinetic laws. It can be shown, however, that for a broad class of substate distributions, the initial slope of the kinetic plot follows an Arrhenius relationship. The activation energy is equal to that of the exponential rate constant measured at high temperature. This result establishes the conditions under which protein data obtained from low-temperature kinetics can be extrapolated to physiological temperature.A protein at thermodynamic equilibrium is subject to transient fluctuations. More than ten years ago, it had been pointed out that volume fluctuations 'if concentrated in one area would produce cavities or channels in the proteins sufficient to allow entry of solvent or probe molecules' [l] and the importance of viscosity-dependent structural fluctuations in enzyme catalysis had been emphasized [2]. A great deal of our present knowledge on protein conformational fluctuations comes from chemical relaxation experiments on oxygen-carrying heme proteins. It is well known that hemoglobin or myoglobin undergo important spectroscopic changes upon binding a ligand (generally oxygen or carbon monoxide) and that ligand dissociation can be triggered, with a relatively high yield, by a light pulse. The subsequent rebinding events can be followed accurately using fast optical absorption spectroscopy.A unique property of heme proteins is that their prosthetic group, the heme, exhibits the elementary reaction of ligand binding in the isolated state. In hemoglobin or myo...

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“…39,67 RR, CD and absorption spectroscopic evidence 32,39,40 suggests that protonation does occur. A similar situation occurs in hemoglobin, where hydrogen bonds to the dioxygen ligand stabilize the oxy form of the protein.…”

Section: Iron Center Geometry In Liganded Forms ± Azidomet-and Oxy-hementioning

confidence: 97%

Hemerythrin

Stenkamp¹

2004

Handbook of Metalloproteins

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Hemerythrin is a non‐heme iron protein that serves as an oxygen transfer or storage protein in several marine invertebrate phyla (sipunculids, brachiopods, priapulids and annelids). Each protein subunit (13 500 kD) binds two iron atoms by histidine, aspartic acid, and glutamic acid side‐chains. The protein carboxylates and a μ‐oxygen atom bridge the iron atoms in a prototypic FeOFe complex that has been extensively studied. One iron binds exogenous ligands including dioxygen and small anions. The protein functions by reversibly adding dioxygen to a deoxy form containing ferrous iron to produce an oxy form containing ferric iron and a peroxo anion.

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Resonance Raman study of oxyhemerythrin and hydroxomethemerythrin. Evidence for hydrogen bonding of ligands to the iron-oxygen-iron center

Cited by 115 publications

References 4 publications

Resonance Raman study on the active-site structure of a cooperative hemerythrin

Resonance Raman study on the active-site structure of a cooperative hemerythrin

Viscosity‐dependent energy barriers and equilibrium conformational fluctuations in oxygen recombination with hemerythrin

Hemerythrin

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