Anisotropy from other Nuclei

The discussion so far has centered on the non-symmetric distribution of local fields surrounding a given nucleus resulting from other nuclei (dipole-dipole interactions) and from electrons (chemical shift anisotropy, CSA). In addition, the nucleus itself may not be symmetric, resulting in a non-symmetric nuclear charge distribution, i.e., an electric quadrupole moment. For nuclei with a spin quantum number, I, of % (e.g., and the quadrupole moment is zero, and no... 

Both siroheme enzymes form ferroheme-NO complexes in which the g value anisotropy appears somewhat smaller than in the corresponding complexes of most other enzymes. The EPR spectra of the complexes somewhat resemble the spectra of the high-temperature myoglobin-NO complexes. The hyperfine splitting from the NO nitrogen nucleus is evident at intermediate g values but is not well resolved. These enzymes are capable of reducing NO to ammonia if supplied with low potential reducing equivalents. Other heme proteins also catalyze oxidation reduction reactions with NO. 

---