Assignment of fluorine nuclear magnetic resonance signals from rabbit cyanomethemoglobin

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Abstract
A fluorine NMR study of cyanomethemoglobin prepared from Hb isolated from rabbits maintained on a diet containing DL-p-fluorophenylalanine is described. Substitution of fluorophenylalanine occurs essentially randomly at all phenylalanine positions of the .alpha.- and .beta.-globin chains; a set of hybrid Hb in which only the .alpha.- and or only the .beta.-chains contain the fluorinated amino acid was prepared and used to ascertain the fluorine NMR signals arising from each chain. The temperature and pH dependences of chemical shifts, spin-lattice relaxation times, 19F{1H} nuclear Overhauser effects and the effect of chemical modification of the .beta.-93 SH- groups were examined. When considered in light of presently available X-ray structures of human and horse Hb, the available data permit a tentative assignment of most signals to particular fluorophenylalanine/phenylalanine positions in the globin sequences.