title: An overview on chlorophylls and quinones in the photosystem I-type reaction centers.
abstract: 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.
authors.affiliation: Institute of Materials Science, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Ohashi
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Iemura
authors.forename: Naoki
authors.initials: N
authors.lastname: Okada
authors.forename: Shingo
authors.initials: S
authors.lastname: Itoh
authors.forename: Hayato
authors.initials: H
authors.lastname: Furukawa
authors.forename: Masaaki
authors.initials: M
authors.lastname: Okuda
authors.forename: Mayumi
authors.initials: M
authors.lastname: Ohnishi-Kameyama
authors.forename: Takuro
authors.initials: T
authors.lastname: Ogawa
authors.forename: Hideaki
authors.initials: H
authors.lastname: Miyashita
authors.forename: Tadashi
authors.initials: T
authors.lastname: Watanabe
authors.forename: Shigeru
authors.initials: S
authors.lastname: Itoh
authors.forename: Hirozo
authors.initials: H
authors.lastname: Oh-oka
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Inoue
authors.forename: Masami
authors.initials: M
authors.lastname: Kobayashi
mesh_terms: D001419:Bacteria / Q000378:metabolism*; D002734:Chlorophyll / Q000737:chemistry*; D019281:Dimerization; D045331:Photosystem I Protein Complex / Q000737:chemistry*; D011809:Quinones / Q000737:chemistry*
chemical_list: D045331:Photosystem I Protein Complex; D011809:Quinones; D002734:Chlorophyll