Electron Spin Resonance in Hæmin, Hæmatin and Hæmoglobin at 4.2° K

Schoffa, G.

doi:10.1038/203640a0

Cited by 22 publications

(10 citation statements)

References 10 publications

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“…At 10 K, hemozoin gave an ESR spectrum indicative of low-spin ferric iron (dominant signals at g = 3.80 and 1.95), while as reported previously, the iron in both hematin and hemin was in a high-spin ferric state (23). As a transition from high to low spin state involves an increase in the electric field strength surrounding the ferric ion (24), these spectra are consistent with the axial hydroxyl or chloride anion in hematin or hemin being replaced by a stronger r-bonding ligand such as a carboxylate in hemozoin.…”

mentioning

confidence: 72%

An iron-carboxylate bond links the heme units of malaria pigment.

Slater

Swiggard

Orton

et al. 1991

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

472

419

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mentioning

confidence: 72%

An iron-carboxylate bond links the heme units of malaria pigment.

Slater

Swiggard

Orton

et al. 1991

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

472

419

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“…Das freie bzw. unspezi6sch im Protein gebundene Ham l&Bt aber wegen der starken Linienverbreiterung bei 77" K noch keine ESR-Signale erkennen [23,24]. Die thermische und Alkali-Denaturierung dagegen fiihrt zur Bildung von Hamoglobin-Hiimochrom(III), dessen g-Werte mit g, = 2,41; g, = 2,25 und g,= 1,91 bestimmt worden sind [24,25].…”

Section: Ergebnisse Und Diskussionunclassified

ESR‐ und CD‐Spektren von pH‐abhängigen Konformationsisomeren des Hämoglobin(III)

Gersonde¹,

Wollmer²

1970

European Journal of Biochemistry

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The native horse haemoglobin(II1) forms two different pH-dependent detergent associates. These two associates were related to the existence of two conformation isomers of the protein [ll]. By aid of the direct verification of the conformation isomers on the native haemoglobin(II1) the possibility should be excluded that the observed associates both originate from only one haemoglobin conformation, which undergoes a pH-depending transformation of the protein structure in the course of the detergent association.ESR und CD techniques confirm the existence of two isomers of the native haemoglobin.According to these findings haemoglobin(II1) is a heterotropic allosteric protein, in which one (at room temperature) or two (at 77" K) proton binding sites interact with the binding site of the 6th ligand mediated by conformation. This interaction can directly be demonstrated in the ESR spectrum of the OH-derivative by the appearance of distinct signals for both isomersThe allosteric and protolytic reactions are described as a circuit process. By aid of computer simulation model curves are calculated, which allow determination of the actual allosteric and protolytic pK-values. A simulation of the pH-dependency of the ellipticity at 340 and 290 nm fits the experimental data, if allosteric pK-values of 7.2 and 7.0 and protolytic pK-values of 8.3 and 8.5 are presumed.The a-helix content remaining constant in the pH-range concerned, the change of conformation affects the t e r h r y structure only.Because of the common pH-dependency the further three low spin signals (gl = 2.91, g, = 2.23, g, = 1.95) have to be attributed to the H,O-Hb(II1) in addition t o the high spin signals (81 = 5.9, gll = 2.0), which characterize the low spin part in the physical high spin-low spin equilibrium of this complex. I f(g' 1 --2.68, g; = 2.16, g; = 1.82; g;' = 2.68, g , = 2.14, gy = 1.77).Further the origin of the conformational active CD bands is discussed. Im Bereich von pH

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“…The observation of two metastable peaks for two reactions of an ion of given composition may arise under two different circumstances. 5 The reactions may take place from the same state of the reacting ion, or the reactions may occur from different states of the reacting ion. Reactions of the first type, which are competitive, have been observed in the mass spectra of some alkanes,6 while reactions of the second type, which are not necessarily competitive, have been observed in the mass spectra of ethanol and benzene.…”

Section: Becausementioning

confidence: 99%

Metastable ion intensities and the comparison of ionic structure

Occolowitz¹

1969

J. Am. Chem. Soc.

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The theoretical basis for comparing the structure of reacting ions by measurement of the relative abundance of metastable ions is examined. It is shown that except for those reactions whose rate constants are of the form kn(E) = Kng(E) there may be some variation in the metastable abundance ratio for reactions of ions of the same structure derived from different origins. The variation can arise because of different energy distributions of precursor molecular ions and different rates of formation of fragment ions. For reactions arising from separate states (or structures) of an ion, the metastable abundance ratio determined for different origins of the ion will be markedly dependent on the energy distribution of the molecular ions. In these cases, the consideration of more than one metastable abundance ratio can indicate which reactions arise from states which are common to all origins of the reacting ion.

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Electron Spin Resonance in Hæmin, Hæmatin and Hæmoglobin at 4.2° K

Cited by 22 publications

References 10 publications

An iron-carboxylate bond links the heme units of malaria pigment.

An iron-carboxylate bond links the heme units of malaria pigment.

ESR‐ und CD‐Spektren von pH‐abhängigen Konformationsisomeren des Hämoglobin(III)

Metastable ion intensities and the comparison of ionic structure

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