Hemoglobin stability: observations on the denaturation of normal and abnormal hemoglobins by oxidant dyes, heat, and alkali

Development of a heme sensor using fluorescently labeled heme oxygenase-1

“…As low as 60% of heme was recovered when hHb was treated with 100 mM NaOH. Because hemoglobin is partially denatured under such alkaline conditions [35], the sensor is considered to detect free heme released from partially denatured hHb. In the case of intact hHb as control, less than 3% of heme was detected, probably due to a residual amount of free heme remaining in the hHb standard.…”

Anthropomorphic breast phantoms with physiological water, lipid, and hemoglobin content for near-infrared spectral tomography

“…Because the melting point of lard is well below the temperature of hemoglobin denaturation, blood can easily be incorporated into this phantom. 35 Adding hemoglobin to the water and lipid phantoms did not substantially alter their water and lipid fractions. Fat content was overestimated in the fibroglandular and tumor phantom sections by ∼15 and 8%, respectively, likely due to the thickness of these compartments (postrefrigeration mixing was not performed in this case) but was <1% in error in the adipose layer.…”

Mechanical Stability of Human Haemoglobins

“…Studies on the denaturation of Hb A using electron-spin resonance spectroscopy have revealed the formation of hemichromes (i.e. low-spin derivatives of ferrihaemoglobin resulting form changes of protein confor mation, such that atoms forming part of amino acid side chains become bound as the sixth ligand of haem iron) as important intermediates [6], That precipitation by mechanical stress may involve hemichrome forma tion is suggested by the finding that (a) hemichromes can be produced by a great variety of denaturing agents [7], (b) formation of Hb H inclusion bodies is accompanied by hemichrome formation [8], (c) the Hbs Bucuresti, Duarte, Köln, M Saskatoon, Shepherds Bush and Zürich have sub stitutions in proximity to the haem iron atom and (d) cyanmethaemoglobin cannot form hemichromes. However, dénaturation by mechanical agitation appears to be less dependent on the oxidation state of the haem iron than on the structure of the subunits of the susceptible haemoglobins.…”

“…This effect of cyanide has been attributed to the increased planari ty of the haem group and the increased stability of the haemoglobin com plex of cyanmethaemoglobin (8).…”