31P chemical shifts as structural probes for heme environments. 31P-NMR study of the binding of trimethyl phosphine to various hemoglobins and myoglobins.

A 31P-NMR study of trimethyl phosphine bound to the heme iron(II) atom in natural myoglobins, hemoglobins and synthetic porphyrin iron(II) shows that the iron-bound trimethylphosphine 31P chemical shifts are sensitive to the presence of globin:separated NMR signals can be observed for 31PMe3 bound to the hemes of the alpha and beta chains. On the basis of previous hemoprotein studies, the markedly high field resonance observed with one of the two PMe3-rabbit subunits is consistent with a specific role of the distal histidine (E7) in rabbit alpha-subunit.