An asymmetric low-spin EPR signal of cytochrome b6 in the cytochrome b6f-complex from spinach chloroplasts

Cytochrome b6 from the chloroplast cytochrome b6f-complex shows an asymmetric gz = 3.85 low-spin EPR signal in addition to a signal at gz = 3.6–3.7, similar to cytochrome b in mitochondrial or bacterial cytochrome bc1-complexes. However, the signal is more unstable and probably represents the highly strained conformation of only part of the low-potential heme in cytochrome b6.