EPR and Mössbauer spectroscopy investigations on the metal ion contents of Sendai virus components.

EPR and Mössbauer spectroscopy indicate that Sendai virus contains iron ions in paramagnetic states. Spectral data show that the iron ions are in an oxidized form (Fe3+), having low and high spin states (S = 1/2 and S = 5/2). On enrichment of Sendai virus with 57Fe, the concentration of Fe3+ ions substantially increases in the virus preparations. The Fe3+ ions in the high spin state appear to be tightly bound to the virus components; they are not significantly removed by dialysis. The five main proteins separated by SDS gel electrophoresis from 57Fe-enriched Sendai virus contain the signal corresponding to the presence of Fe3+ ions in the high spin state. The concentration of Fe3+ ions is, however, about five times higher in the HN polypeptide than in the other four components. It is suggested that Fe3+ (5/2) ions might be a structural component of the Sendai virus HN polypeptide.