An overview on chlorophylls and quinones in the photosystem I-type reaction centers.
Minor but key chlorophylls (Chls) and quinones in photosystem (PS) I-type reaction centers (RCs) are overviewed in regard to their molecular structures. In the PS I-type RCs, the prime-type chlorophylls, namely, bacteriochlorophyll (BChl) a' in green sulfur bacteria, BChl g' in heliobacteria, Chl a' in Chl a-type PS I, and Chl d' in Chl d-type PS I, function as the special pairs, either as homodimers, (BChl a')(2) and (BChl g')(2) in anoxygenic organisms, or heterodimers, Chl a/a' and Chl d/d' in oxygenic photosynthesis. Conversions of BChl g to Chl a and Chl a to Chl d take place spontaneously under mild condition in vitro. The primary electron acceptors, A (0), are Chl a-derivatives even in anoxygenic PS I-type RCs. The secondary electron acceptors are naphthoquinones, whereas the side chains may have been modified after the birth of cyanobacteria, leading to succession from menaquinone to phylloquinone in oxygenic PS I.
Ohashi
Shunsuke
S
Institute of Materials Science, University of Tsukuba, Tsukuba, Ibaraki, Japan.
Iemura
Tatsuya
T
Okada
Naoki
N
Itoh
Shingo
S
Furukawa
Hayato
H
Okuda
Masaaki
M
Ohnishi-Kameyama
Mayumi
M
Ogawa
Takuro
T
Miyashita
Hideaki
H
Watanabe
Tadashi
T
Itoh
Shigeru
S
Oh-oka
Hirozo
H
Inoue
Kazuhito
K
Kobayashi
Masami
M
D001419:Bacteria / Q000378:metabolism*; D002734:Chlorophyll / Q000737:chemistry*; D019281:Dimerization; D045331:Photosystem I Protein Complex / Q000737:chemistry*; D011809:Quinones / Q000737:chemistry*
D045331:Photosystem I Protein Complex; D011809:Quinones; D002734:Chlorophyll