15N NMR studies of the binding of 15N-labeled cyanide to various hemoglobins in intact erythrocyte.

¹⁵N-labeled cyanide binding to methemoglobins in intact erythrocytes has been studied by ¹⁵N NMR. The addition of C¹⁵N^? to human and dog hemoglobins in erythrocyte afforded hyperfine-shifted two ¹⁵N signals due to the C¹⁵N bound to ferric iron of the different heme-units. Single and three distinct signals were observed for rat and rabbit hemoglobins in erythrocyte. These C¹⁵N resonance positions are sensitive both to the structural difference in the hemoglobin subunits and to the variety of the animal sources. The C¹⁵N spectral difference between solution and intact hemoglobin cyanide is also discussed in relation to a possible change in the intra- and extracellular pH values.