Proton NMR studies of horse ferricytochrome c Completion of the assignment of the well resolved hyperfine shifted resonances

¹H NMR saturation transfer and nuclear Overhauser effect (NOE) measurements have been used together with two-dimensional spectra to complete the assignment of the well resolved hyperfine shifted resonances in the spectrum of horse ferricytochrome c and obtain their shifts in the reduced protein. New assignments include the β-CH₂ protons of Met-80, both ring protons of His-18, and the α-CH₂ of Gly-29 and δ-CH₂ of Pro-30, which resonate surprisingly far upfield despite the absence of any Fermi contact contribution to the shift.