Minor but key chlorophylls in photosystem II.
A 'metal-free' chlorophyll (Chl) a, pheophytin (Phe) a, functions as the primary electron acceptor in PS II. On the basis of Phe a/PS II = 2, Phe a content is postulated as an index for estimation of the stoichiometry of pigments and photosystems. We found Phe a in a Chl d-dominant cyanobacterium Acaryochloris marina, whereas Phe d was absent. The minimum Chl a:Phe a ratio was 2:2, indicating that the primary electron donor is Chl a, accessory is Chl d, and the primary electron acceptor is Phe a in PS II of A. marina. Chl d was artificially formed by the treatment of Chl a with papain in aqueous organic solvents. Further, we will raise a key question on the mechanisms of water oxidation in PS II.
Kobayashi
Masami
M
Institute of Materials Science, University of Tsukuba, Tsukuba 305-8573, Japan. masami@ims.tsukuba.ac.jp
Watanabe
Satoru
S
Gotoh
Takanori
T
Koizumi
Hajime
H
Itoh
Yuka
Y
Akiyama
Machiko
M
Shiraiwa
Yoshihiro
Y
Tsuchiya
Tohru
T
Miyashita
Hideaki
H
Mimuro
Mamoru
M
Yamashita
Takashi
T
Watanabe
Tadashi
T
D002734:Chlorophyll / Q000737:chemistry* / Q000378:metabolism; D000077194:Chlorophyll A; D004579:Electron Transport; D004735:Energy Transfer; D056890:Eukaryota / Q000737:chemistry / Q000378:metabolism; D015394:Molecular Structure; D028528:Petroselinum / Q000737:chemistry / Q000378:metabolism; D010674:Pheophytins / Q000737:chemistry* / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000737:chemistry* / Q000378:metabolism
D010674:Pheophytins; D045332:Photosystem II Protein Complex; D002734:Chlorophyll; C061694:pheophytin a; C107509:chlorophyll d; D000077194:Chlorophyll A