title: Reversed-phase HPLC determination of chlorophyll a' and phylloquinone in Photosystem I of oxygenic photosynthetic organisms. Universal existence of one chlorophyll a' molecule in Photosystem I.
abstract: Chlorophyll (Chl) a', the C132-epimer of Chl a, is a constituent of the primary electron donor (P700) of Photosystem (PS) I of a thermophilic cyanobacterium Synechococcus (Thermosynechococcus) elongatus, as was recently demonstrated by X-ray crystallography. To determine whether PS I of oxygenic photosynthetic organisms universally contains one molecule of Chl a', pigment compositions of thylakoid membranes and PS I complexes isolated from the cyanobacteria T. elongatus and Synechocystis sp. PCC 6803, the green alga Chlamydomonas reinhardtii, and the green plant spinach, were examined by simultaneous detection of phylloquinone (the secondary electron acceptor of PS I) and Chl a' by reversed-phase HPLC. The results were compared with the Chl a/P700 ratio determined spectrophotometrically. The Chl a'/PS I ratios of thylakoid membranes and PS I were about 1 for all the organisms examined, and one Chl a' molecule was found in PS I even after most of the peripheral subunits were removed. Chl a' showed a characteristic extraction behaviour significantly different from the bulk Chl a in acetone/methanol extraction upon varying the mixing ratio. These findings confirm that a single Chl a' molecule in P700 is the universal feature of PS I of the Chl a-based oxygenic photosynthetic organisms.
authors.affiliation: Institute of Industrial Science, The University of Tokyo, Japan.
authors.forename: Akimasa
authors.initials: A
authors.lastname: Nakamura
authors.forename: Masahiko
authors.initials: M
authors.lastname: Akai
authors.forename: Emi
authors.initials: E
authors.lastname: Yoshida
authors.forename: Takashi
authors.initials: T
authors.lastname: Taki
authors.forename: Tadashi
authors.initials: T
authors.lastname: Watanabe
mesh_terms: D000096:Acetone / Q000737:chemistry; D000818:Animals; D016825:Chlamydomonas reinhardtii / Q000378:metabolism; D002734:Chlorophyll / Q000031:analogs & derivatives* / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D000458:Cyanobacteria / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D008027:Light; D045342:Light-Harvesting Protein Complexes; D000432:Methanol / Q000737:chemistry / Q000494:pharmacology; D010100:Oxygen / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D010788:Photosynthesis; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D018724:Spinacia oleracea / Q000378:metabolism; D020524:Thylakoids / Q000378:metabolism; D013997:Time Factors
chemical_list: D045342:Light-Harvesting Protein Complexes; D010455:Peptides; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D000096:Acetone; D002734:Chlorophyll; C085815:chlorophyll a'; C001785:chlorophyll P 700; D010100:Oxygen; D000432:Methanol