Denaturation of Hemoglobins by Alkali

Haurowitz, Felix; Hardin, Richard L.; Dicks, Martha W.

doi:10.1021/j150512a003

Cited by 44 publications

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“…Hollecher and Buckley demonstrated the efficacy of EPR spectroscopy in measurements of Met-Hb over the range from pH 3 to pH 12 41 . Others have shown acid induced denaturation to occur below pH 4 42 and alkaline denaturation to occur above pH 11 43 . Using a pH range similar to ours, Svistunenko et al conducted an EPR investigation of the pH dependence of Met-Hb hemichrome species, noting that all species detected were also present in whole blood 17 .…”

Section: Discussionmentioning

confidence: 99%

EPR Spectroscopy of Nitrite Complexes of Methemoglobin

2010

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The chemical interplay of nitrogen oxides (NO's) with hemoglobin (Hb) has attracted considerable recent attention because of its potential significance in the mechanism of NO-related vasoactivity regulated by Hb. An important theme of this interplayredox coupling in adducts of heme iron and NO'shas sparked renewed interest in fundamental studies of FeNO x coordination complexes. In this Article, we report combined UV−vis and comprehensive electron paramagnetic resonance (EPR) spectroscopic studies that address intriguing questions raised in recent studies of the structure and affinity of the nitrite ligand in complexes with FeIII in methemoglobin (metHb). EPR spectra of metHb/NO2 − are found to exhibit a characteristic doubling in their sharper spectral features. Comparative EPR measurements at X- and S-band frequencies, and in D2O versus H2O, argue against the assignment of this splitting as hyperfine structure. Correlated changes in the EPR spectra with pH enable complete assignment of the spectrum as deriving from the overlap of two low-spin species with g values of 3.018, 2.122, 1.45 and 2.870, 2.304, 1.45 (values for samples at 20 K and pH 7.4 in phosphate-buffered saline). These g values are typical of g values found for other heme proteins with N-coordinated ligands in the binding pocket and are thus suggestive of N-nitro versus O-nitrito coordination. The positions and shapes of the spectral lines vary only slightly with temperature until motional averaging ensues at ∼150 K. The pattern of motional averaging in the variable-temperature EPR spectra and EPR studies of FeIIINO2 −/FeIINO hybrids suggest that one of two species is present in both of the α and β subunits, while the other is exclusive to the β subunit. Our results also reconfirm that the affinity of nitrite for metHb is of millimolar magnitude, thereby making a direct role for nitrite in physiological hypoxic vasodilation difficult to justify.

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Section: Discussionmentioning

confidence: 99%

EPR Spectroscopy of Nitrite Complexes of Methemoglobin

2010

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“…2). Haurowitz, Hardin, and Dicks (1954) have shown that the configurational changes associated with de-oxygenation of bovine and rabbit haemoglobin leads to a decrease in the resistance to alkaline denaturation. Also variations in the resistance of haemoglobins to alkaline denaturation are usually associated with differences in their oxygen affinity (Jonxis 1949).…”

Section: Discussionmentioning

confidence: 99%

Haemoglobin and Erythrocyte Potassium Types in Sheep and their Influence on Oxygen Dissociation and Haemoglobin Denaturation

Dawson¹,

Evans²

1962

Aust. Jnl. Of Bio. Sci.

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SummaryThe influence of haemoglobin type and erythrocyte potassium concentration on oxygen dissociation curves and rate of denaturation of haemoglobin by alkali have been studied in Southdown sheep.A significant difference has been found between haemoglobin types in respect to their oxygen dissociation curves and rate of alkali denaturation.A significant difference was found between the oxygen dissociation curves of high potassium (HK) and low potassiu~ (LK) sheep. No significant difference was found between HK and LK sheep in respect to the rate of denaturation of their haemoglobin by alkali.An association has been found, within a potassium group, between erythrocyte potassium concentration, oxygen dissociation curves, and rate of denaturation of haemoglobin by alkali. The possible significance of the results is discussed.

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“…*The Relative Stabilities of the Skeletal-Muscle Myosins of some Animals BY J. J. CONNELL Torry Re8earch Station, Aberdeen, Department of Scientific and Indu8trial Research (Received 27 February 1961) It is sometimes found that the stabilities of the members of a series of closely related proteins differ widely, examples being the haemoglobins and the collagens. It has been proposed (Haurowitz, Hardin & Dicks, 1954) that the relative stabilities towards alkaline denaturation of the haemoglobins ofvarious animals are due to different degrees of complementariness of the globin molecules to the haem group. Differences in the hydrothermal stability of collagens from certain animals have been ascribed to differences in hydroxyproline content (Gustavson, 1955;Rigby & Spikes, 1960).…”

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The relative stabilities of the skeletal-muscle myosins of some animals

Jj¹

1961

Biochemical Journal

119

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ALKYLATING AGENTS AND NUCLEIC ACIDS 503 only if alkylation on each strand at nearly opposite points had occurred. At low degrees of alkylation by monofunctional agents this would occur only rarely, being in proportion to the square of the degree of alkylation; with difunctional agents about a quarter of the alkylations would be of this type. It would also be expected that fission of the DNA molecule could seriously interfere with its biological function. SUMMARY 1. The rates and extents of alkylation of ribonucleic acid and of deoxyribonucleic acid in neutral aqueous solution at 370 by a variety of alkylating agents have been determined. 2. Alkylation has been shown to occur at N-7 of guanine moieties, monofunctional agents yielding 7-alkylguanines, and difunctional agents yielding in addition di(guanin-7-yl) derivatives. 3. Alkylated ribonucleic acid is stable in neutral aqueous solution but alkylated deoxyribonucleic acid decomposes with loss of the alkylated guanine products. 4. The extent of binding has been determined of 3H-labelled myleran, 35S-labelled mustard gas and of 2-hydroxyethyl 2-chloroethyl [35S]sulphide to cellular constituents of the Ehrlich-ascites tumour and of 3H-labelled myleran to leukaemic cells in the mouse. 5. The only difference found in vivo or in vitro for reaction of mustard gas and 2-hydroxyethyl 2-chloroethyl sulphide with nucleic acids is that mustard gas yields di-(P-guanin-7-yl) sulphide. 6. Mustard gas is at least 30 times as effective as 2-hydroxyethyl 2-chloroethyl sulphide as an inhibitor of the growth of an ascites tumour in the mouse. 7. The mode of combination of monofunctional and of difunctional alkylating agents with nucleic acids is discussed in terms of the Crick-Watson model for the structure of deoxyribonucleic acid. 8. The possible relationship between the alkyl-ation of deoxyribonucleic acid and the biological properties of the alkylating agents is discussed. We thank Dr J. F. A.

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Denaturation of Hemoglobins by Alkali

Cited by 44 publications

References 0 publications

EPR Spectroscopy of Nitrite Complexes of Methemoglobin

EPR Spectroscopy of Nitrite Complexes of Methemoglobin

Haemoglobin and Erythrocyte Potassium Types in Sheep and their Influence on Oxygen Dissociation and Haemoglobin Denaturation

The relative stabilities of the skeletal-muscle myosins of some animals

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