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Observation of symmetric denaturation of hemoglobin subunits by electrospray ionization mass spectrometry
Author(s) -
Wang Xian,
Zhao Wenjie,
Lin Xin,
Su Bo,
Liu Jianfeng
Publication year - 2010
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.1843
Subject(s) - chemistry , electrospray ionization , globin , circular dichroism , heme , acetonitrile , mass spectrometry , denaturation (fissile materials) , solvent , hemeprotein , electrospray , hemoglobin , methanol , chromatography , crystallography , nuclear chemistry , organic chemistry , enzyme
Abstract Electrospray ionization mass spectrometry (ESI‐MS) has been used to characterize the denaturation of porcine hemoglobin (Hb) induced by solvent changes. This work provides evidence for the symmetric nature of Hb denaturation and demonstrates that heme losses from α‐ and β‐monomers occur in parallel, in response to the addition of acid and organic co‐solvents in solution. When subject to one of the following solution conditions (pH 3.2–4.0 or 15–30% acetonitrile‐water or 30–45% methanol‐water solution), α‐ and β‐globins undergo symmetric dissociation to release the heme groups, which is detected by ESI‐MS. Circular dichroism (CD) and fluorescence spectroscopy (FS) data show that the acid‐induced and organic solvent‐induced heme release, as observed in the mass spectra, can probably be ascribed to different aspects of the conformational changes taking place in the protein. The acidity of the solvent has a significant effect on the secondary structure, whereas organic content level in solution (15–30% acetonitrile or 30–45% methanol) tends to destroy the tertiary structure of Hb globins, both leading to release of the heme from each subunit. Copyright © 2010 John Wiley & Sons, Ltd.