Structural studies of some polynuclear iron proteins

Abstract

The coordination structure and electronic configuration of iron(III) bound in a polynuclear fashion to a number of proteins have been investigated by a variety of physical methods. These have included the temperature dependence of the magnetic susceptibility, electron spin resonance spectroscopy, electronic absorption spectroscopy at low temperatures, vibrational spectroscopy, X-ray analysis, Mossbauer spectroscopy down to helium temperature, and electron spectroscopy for chemical analysis (ESCA). The proteins investigated included the iron transport protein transferrin, the phosphoglycoprotein phosvitin, the gastric juice glycoprotein gastroferrin, and the two iron storage proteins ferritin and hemosiderin. On the basis of the results obtained by these techniques the structural relationship of the iron to the protein and to other iron atoms present in the polynuclear complex was clarified. Structural models for these relationships were proposed for the proteins listed. The implications of these results for the biological role of iron have been considered.