Mössbauer Spectroscopy of Cytochrome c

The cytochrome $c$ of $T$ . utilis grown in a ⁵⁷‐enriched medium has been investigated by Mössbauer spectrometry over a wide temperature range. The ferric cytochrome, in both lyophilized and frozen‐solution form, shows magnetic hyperfine interaction at low temperatures and resembles some of the low‐spin homoglobins. Spectra are in good agreement with calculations based on $g$ values of horse‐heart ferricytochrome $c$ . The ferrous cytochrome exhibits a simple temperature‐independent quadrupole splitting of 1.18 ± 0.05 mm/sec. Measurements in applied field indicate that $V_{\mathrm{zz}}\text{\hspace{0.17em}>\hspace{0.17em}0}$ , and $\text{η\hspace{0.17em}∼\hspace{0.17em}0.5}$ .