Editing Photosystem I (section)

=== Phylloquinone ===

A [[phylloquinone]], sometimes called vitamin K{{sub|1}},<ref name="itoh">{{cite journal|last1=Itoh|first1=Shigeru|last2=Iwaki|first2=Masayo|name-list-style=vanc|year=1989|title=Vitamin K{{sub|1}} (Phylloquinone) Restores the Turnover of FeS centers of Ether-extracted Spinach PSI Particles|journal=FEBS Letters|volume=243|issue=1|pages=47–52|doi=10.1016/0014-5793(89)81215-3|doi-access=free|s2cid=84602152}}</ref> is the next early electron acceptor in PSI. It oxidizes A{{sub|1}} in order to receive the electron and in turn is re-oxidized by F{{sub|x}}, from which the electron is passed to F{{sub|b}} and F{{sub|a}}.<ref name="itoh"/><ref>{{cite journal | vauthors = Palace GP, Franke JE, Warden JT | title = Is phylloquinone an obligate electron carrier in photosystem I? | journal = FEBS Letters | volume = 215 | issue = 1 | pages = 58–62 | date = May 1987 | pmid = 3552735 | doi = 10.1016/0014-5793(87)80113-8 | s2cid = 42983611 | doi-access = free | bibcode = 1987FEBSL.215...58P }}</ref> The reduction of F<sub>x</sub> appears to be the rate-limiting step.<ref name=Grotjohann/>