Cytochrome b6 from isolated cytochrome b6f complexes

Cytochrome b 6 from spinach chloroplasts (either within the purified cytochrome b 6 f complex, or in its isolated form) exhibits two spectral species, which correspond to two midpoint potentials. This can be demonstrated by low temperature difference spectroscopy at fixed redox potentials. The high potential form of cytochrome b 6 has a split α‐peak at 557.5 and 561.5 nm, the low potential form has a symmetrical α‐peak at 560.5 nm. Similar results were obtained with cytochrome b 6 in the isolated cytochrome b 6 f complex from the cyanobacterium Anabaena variabilis.