David B. Viscio

Carbon-13-iron-57 spin coupling as a new structural probe on hemoproteins. Carbon-13 NMR spectrum of iron-57-enriched carbonyl myoglobin.

Abstract Carbon-13 Fourier transform nmr has been used to make the first observation of a carbon-13-iron-57 spin-spin coupling constant in a protein, sperm whale carbonyl myoglobin enriched to 90% in both iron-57 and carbon-13. The coupling constant, 27.1±0.2 Hz, is found to be essentially identical to that of a model compound, supporting the view that the carbonyl is not tilted with respect to the heme plane in solution. Such carbon-13-iron-57 couplings, and the resultant iron-57 chemical shifts obtained from decoupling experiments, should provide valuable new tools for studying the different affinity states of tetrameric hemoglobins.