Robert R. Gagne

Mössbauer spectroscopy of hemoglobin model compounds: Evidence for conformational excitation

Zero‐field Mossbauer spectra of a model compound for hemoglobin, capable of undergoing reversible oxygenation, were recorded at various temperatures. A pair of peaks with temperature‐dependent quadrupole splitting and linewidth were observed. The results have been interpreted in terms of a model which is consistent with previous x‐ray studies and which provides for relaxation effects as the molecule assumes two possible conformational states. In terms of the proposed model, the two conformational states have been characterized by their energy separation and their respective electric field gradient tensors. The relaxation rate at each temperature has also been determined.

Synthetic models for the oxygen-binding hemoproteins

The oxygen binding hemoproteins hemoglobin (Hb), myoglobin (Mb), and cytochrome P-450 are important to the biological transport, storage, and metabolism of oxygen. Nevertheless the nature of the coordinate link between iron and dioxygen in these hemoproteins has not been defined at the atomic level. Furthermore the way in which the glogin proteinheme interaction directs reversible oxygen binding has been obscure. My students have addressed and partially clarified these issues by preparing crystalline iron(II) porphyrin-dioxygen complexes.1–5 These remarkable Mb models which reversibly bind oxygen in solution or in the solid state at ambient temperature have been characterized by Mossbauer1,5, ir spectra4 and X-ray crystallographic analysis.2