Near-infrared absorption and circular dichroism spectra of ferrocytochrome c: d-d transitions

Transitions to the lowest crystal field singlet states of horse heart ferrocytochrome c have been identified from absorption and circular dichroism spectra in the wavelength region 5700–10 000 Å. The results are correlated with crystal field and molecular orbital theoretical predictions. The Dq value for the porphyrin ring of ferrocytochrome c is found to be between 1700 and 1900 cm−1, in excellent agreement with the extended Hückel calculations of Zerner, Gouterman, and Kobayashi.