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Circular dichroism studies of freeze-drying-induced conformational changes in human hemoglobin

✍ Scribed by Christian Thirion; Dominique Larcher; Bernard Chaillot; Pierre Labrude; Claude Vigneron

Publisher: Wiley (John Wiley & Sons)
Year: 1983
Tongue: English
Weight: 728 KB
Volume: 22
Category: Article
ISSN: 0006-3525
DOI: 10.1002/bip.360221105

No coin nor oath required. For personal study only.

✦ Synopsis

Freeze-drying of hemoglobin leads to the formation of a significant amount of methemoglobin. It is possible to decrease this transformation in the presence of protective compounds. The mechanism of action of these protectors is presently unknown. Spectroscopic absorption and CD spectra between 190 and 700 nm are presented for samples of hemoglobin freeze-dried with or without protection and for control solutions of oxyhemoglobin and methemoglobin. The interpretation of the dichroic spectra allows us to observe the secondary, tertiary, and quaternary structure changes that hemoglobin undergoes with freeze-drying. The results indicate that the absence of a protector weakly influences the conformation in the vicinity of the heme and increases the helicity of protein chains from 75 to 81%. Furthermore, experimental data, in agreement with electron-spin resonance measurements, suggest that the protective effect is not the result of a direct bond between the iron and the compound added.

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