Cytochromec₆

Abstract

Cytochrome c 6 , or its functional analog copper protein plastocyanin, mediates the intrathylakoidal photosynthetic electron transfer from the always dimeric cytochrome b 6 f complex to the monomeric and/or trimeric Photosystem I (PS I) complex. The high‐potential monoheme protein belongs to the omnipresent cytochrome c family and is mainly characterized by its highly conserved N‐terminal heme coordinating sequence C–X–X–C–H and a low spin heme‐iron with methionine and histidine as axial ligands. Despite the excellent knowledge about synthesis, structures, and physical properties of cytochrome c 6 from various organisms, the real molecular events that occur during its reduction by cytochrome b 6 f and its oxidation by the reaction center of PS I are presently uncertain. In addition, the specific role of cytochrome c 6 within the hydrogen metabolism in an anaerobic environment is in the focus of interest. However, the presentation of established information about cytochrome c 6 is accompanied by a brief discussion on the biochemical and physiological aspects concerning function, association, and changes of the molecule.