We are developing iron-57 and deuterium Magnetic Resonance (NMR) as an experimental method for use in the Biomedical Sciences. Numerous molecules essential to life are constructed about iron-containing central cores. Among these are hemoglobin, ferridoxin and the cytochromes. To date, no physical chemical methods have allowed direct study of the central metal enviroment of these proteins. Iron-57 NMR, i.e., the direct detection of the iron NMR signal, is being developed for that purpose. Earlier, we reported results of an iron-57 NMR investigation of characteristic relaxation times and chemical shifts of some iron compounds. The data furnished information on the chemical shift range of iron coordinated to nitrogen, substituent effects on iron-57 chemical shifts, and relaxation mechanisms for iron-57, and thus provide the basic parameters needed for further development of iron-57 NMR. Most recently, the first observation of 57Fe NMR in a protein, carbonmonoxymyoglobin, was published together with a determination of 57Fe relaxation times and chemical shift anisotropy. We have now expanded this project to include a study of the field dependent H-2 NMR of iron porphyrins. The work confirms the partial orientation of iron porphyrins in the field and allows the determination of magnetic anisotropies.
