Interaction of Arsine with Hemoglobin in Arsine-Induced Hemolysis

The mechanism of arsine (AsH3) toxicity is not completely understood, but hemoglobin (Hb) has long been recognized as a necessary component of the overall mechanism of AsH3-induced hemolysis. In this study, the role of Hb in AsH3-induced hemolysis was investigated. The purpose was to determine whether exposure to AsH3 altered the structure of the heme or globin constituents of Hb. Arsine was incubated with isolated, human oxyhemoglobin (oxyHb) and carboxyhemoglobin (carboxyHb), and the release of heme and formation of AsH3-induced hemoglobin modifications were examined. Arsine increased the amount of heme released from oxyHb by 18%. When carboxyHb was incubated with AsH3, there was no change in heme release, suggesting that the sixth ligand position on the heme iron may be critical in the interaction with AsH3. Arsine-Hb interactions were studied by mass spectral analysis of heme, alpha-chain globin, and beta-chain globin. Arsine had no significant effect on the alpha- or beta-chain LCMS spectra in oxyHb and carboxyHb, but in oxyHb, arsine consistently increased the frequency of methyl acetate ion fragment (.CH2OOH, m/z = 59) loss from heme in the matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) spectra. The formation of Hb-protein crosslinks was investigated by Western blotting using an anti-Hb antibody in isolated membranes from AsH3-treated erythrocytes, but no Hb-membrane adducts were found. These results suggest that the interaction between AsH3 and hemoglobin result in an increase in heme release which may contribute to the hemolytic mechanism of AsH3.