X-ray absorption spectroscopy of the dimeric iron site in azidomethemerythrin from Phascolopsis gouldii.

X-ray absorption spectroscopy has been used to study the dimeric iron center in azidomethemerythrin from Phascolopsis gouldii. Absorption edge data confirm that the two iron atoms are present as Fe(III) and suggest a hexa-coordination site for each of the iron atoms. The extended x-ray absorption fine structure (EXAFS) analysis provides direct structural evidence of a mu-oxo bridge between the two iron atoms at an average Fe-O distance of 1.

Multiple conformations at functional site of hemerythrin: Evidence from resonance Raman spectra.

Resonance Raman spectra were obtained for monomeric oxymyohemerythrin and for the azide, thiocyanate, cyanate, cyanide, and fluoride adducts of metmyohemerythrin. The internal ligand vibrations in these complexes appear at essentially the same frequencies as those in the corresponding complexes of octameric hemerythrin. Likewise the Fe-O frequencies in H(2) (16)O do not depend on quaternary structure of the protein.