Photooxidation of high‐potential (c559, c556) and low‐potential (c552) hemes in the cytochrome subunit of Rhodopseudomonas viridis reaction center

Abstract
The photooxidation of c 559, c 556, and c 552 hemes in Rhodopseudomonas viridis cytochrome has been characterized by light‐induced FTIR difference spectroscopy. Apart from the common features at 1659 cm−1 and 1561/1551 cm−1 which could arise from one (or possibly two) peptide bond(s), no evidence for major structural rearrangement of the polypeptide backbone was observed. A significant difference with respect to redox‐induced FTIR spectra of cytochrome c is the absence of the Tyr marker at 1514/1518 cm−1 in Rps. viridis cytochrome, indicating that the localized shift of a Tyr side chain observed between ferro‐ and ferri‐cytochrome c does not occur in Rps. viridis cytochrome.