Electron paramagnetic resonance of beef-heart ferricytochrome c.

We have observed an anisotropic EPR spectrum in a frozen solution of the low-spin (~=i) ~e~op~tein ferricytochrome c. These results are interpreted in terms of the theory for ~e low-sp~ femc lon m an octahedral crystal field which is subject to an (axial) distortion along. the a:os perpendicu~r ~ the heme plane and a (rhombic) distortion in the plane of the heme, and a spm--{)rblt cons~t which 1:' less than that found in the free ion. This model also leads to calculated values for the effective magnetic moment which agree well with experiment.