RED-CELL AGING - FE-HEME STRUCTURE IN DENATURED HEMOGLOBINS BY XANES

The Fe-heme structure of hemoglobin under various 'in vitro' denaturin g conditions has been investigated by Xray Absorbption Near Edge Struc ture (XANES) spectroscopy at the Fe Kedge. The Fe3+ ion in denatured h emoglobin is found both in low-spin and high-spin rhombic fields. New structural information on the low-spin forms (hemichromes), complement ary to that already furnished by Electron Paramagnetic Resonance (EPR) , is achieved. The presence and relevance of these denatured forms in the 'in vivo' process of red cell aging is discussed.