• Proceedings of the Korean Society of Potoscience Conference
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• spring
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• pp.40-42
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• 2003

• Journal of Photoscience
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• v.9 no.2
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• pp.353-355
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• 2002

We prepared 3-(1-hydroxyethyl)-bacteriopyrochlorophy11-a (3) possessing magnesium atom and phytyl ester from modification of natural bacteriochlorophyll(BChl)-a. A dichloromethane solution of (3$^1$R) and (3$^1$S)-3 was diluted with 100~1000 fold volume of cyclohexane to give new species absorbing near-infrared lights. The resulting Q, maximum of (3$^1$R)-3 was 860 nm and red-shifted by 2150 $cm^{-1}$ / from the monomeric. In the nonpolar organic solvent, epimeric (3$^1$S)-3 showed a 1ess red-shifted peak at 798 nm as well as a residual monomeric band. Such visible spectra indicated that 3 diastereose1ectively aggregated in cyclohexane to afford oligomers possessing a simi1ar supramolecular structure with chlorosomal aggregates of natural BChl-d, 7,8-dehydro-form of 3.

• Journal of Photoscience
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• v.9 no.2
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• pp.74-77
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• 2002

Chlorophyll (Chi) d was assigned to an antenna pigment of red algae in 1943, but its presence and function in red algae have not been necessarily clear for a long time. In 1996, it was shown that Chi d functioned as a major antenna pigment in a peculiar oxygenic photosynthetic prokaryote, Acaryochloris marina, isolated as a symbiont of a colonial ascidian from coral reefs. This finding evoked the necessity for reexamination of the presence and function of Chi d in red algae. We found Chi d in methanol-extract from several marine red algae, and the relative content was high in one species, Ahnfeltiopsis flabelliformis. Absorption and fluorescence spectra, HPLC analysis, and NMR and mass spectroscopy characterized Chi d extracted from the red algal thalli, and those were essentially identical to those of Chi d isolated from A. marina. However, micro-spectrophotometric analysis suggested that Chi d was not an actual constituent of the red algae but came from epiphyte(s) attached to surface of red algal thalli.

• Journal of Photoscience
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• v.9 no.2
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• pp.350-352
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• 2002

We examined the bacteriochlorophyill/bacteriopheophytin ratios in several species of purple bacteria containing only LHI. The pigment ratios depended greatly on species. Further, Rhodospirillum rubrum showed wide variation when grown under different light intensity, and Rhodobium marinum showed significant variation from culture to culture even under the same light conditions. The protein ratios of a/RC and $\beta$/RC estimated by SDS-PAGE of chromatophores of Rsp. rubrum and Rbi. marinum exhibited the ratio of $\beta$/$\alpha$ > 1. These findings gave us the novel idea that there are two types of LHl; one is a C-shaped open antenna composed by $\alpha$$\beta$ units surrounding a RC, and another is a small closed ring antenna composed by $\alpha$$\beta$ units located peripherally in a variable ratio to the core complex like LH2.

• BMB Reports
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• v.38 no.4
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• pp.481-485
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• 2005

The response of Spirulina (Arthrospira) platensis to high salt stress was investigated by incubating the cells in light of moderate intensity in the presence of 0.8 M NaCl. NaCl caused a decrease in photosystem II (PSII) mediated oxygen evolution activity and increase in photosystem I (PSI) activity and the amount of P700. Similarly maximal efficiency of PSII (Fv/Fm) and variable fluorescence (Fv/Fo) were also declined in salt-stressed cells. Western blot analysis reveal that the inhibition in PSII activity is due to a 40% loss of a thylakoid membrane protein, known as D1, which is located in PSII reaction center. NaCl treatment of cells also resulted in the alterations of other thylakoid membrane proteins: most prominently, a dramatic diminishment of the 47-kDa chlorophyll protein (CP) and 94-kDa protein, and accumulation of a 17-kDa protein band were observed in SDS-PAGE. The changes in 47-kDa and 94-kDa proteins lead to the decreased energy transfer from light harvesting antenna to PSII, which was accompanied by alterations in the chlorophyll fluorescence emission spectra of whole cells and isolated thylakoids. Therefore we conclude that salt stress has various effects on photosynthetic electron transport activities due to the marked alterations in the composition of thylakoid membrane proteins.

• Applied Biological Chemistry
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• v.23 no.1
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• pp.73-83
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• 1980

The light harvesting pigment proteins of dinoflagellates exhibit essentially 100% efficient energy transfer from carotenoid (peridinin) to chlorophyll a within the antenna pigment complexes. The high efficiency of solar energy harvesing (particularly blue light) for photosynthesis in dinoflagellates is attributable to the unique molecular topography of peridinin and chlorophyll e within the protein crevice. The mechanisms of energy transfer from carotenoids to chlorophyll in higher plants have also been discussed in comparison with the dinoflagellate antenna pigment complexes. As an example of solar energy harvesting, particularly red light, for photosynthesis in algae, the molecular topography and energy transfer in the photosynthetic accessory pigment protein, Chroomonas phycocyanin, have also been discussed.

• Journal of Photoscience
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• v.9 no.2
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• pp.66-69
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• 2002

Zinc chlorin 1 possessing tertiary 3$^1$_hydroxy and 13$^1$-oxo groups was synthesized as a model for the antenna chlorophylls of photosynthetic green bacteria. Self-aggregation of 1 in nonpolar organic solvents was examined and compared to 2 and 3 possessing a secondary and primary 3$^1$_hydroxy group, respectively. Zinc chlorin 1 self-aggregated in I％(v/v) CH$_2$Cl$_2$-hexane to form oligomers and showed a red-shifted Qy maximum at 704 nm compared to the monomer (648 nm in CH$_2$CI2$_2$). This red-shift is larger than that of 3$^1$S-2 (648 to 697 nm) and comparable to that of3$^1$R-2 (648 to 705 nm), but smaller than that of 1 (648 to 740 nm), indicating that while a single 3$^1$-methyl group (primary to secondary OH) suppressed tight and/or extended aggregation, the additional 3$^1$-methyl group (secondary to tertiary OH) did not further suppress aggregation. The relative stability of the aggregates was in the order 3> 3$^1$R-2∼ 1 > 3$^1$S-2 as determined by visible spectral analyses. Molecular modeling calculations on oligomers of zinc chlorins 1, 3$^1$ R-2 and 3 gave similar well-ordered energy-minimized structures, while 3 stacked more tightly than 3$^1$ R- 2 and 1. In contrast, 3$^1$S-2 gave a relatively disordered (twisted) structure. The calculated oligomeric structures could explain the visible spectral data of 1-3 in nonpolar organic solvents. Moreover, self- aggregation of synthetic zinc 13$^1$_oxo-hlorins 4-6 possessing a 2-hydroxyethyl, 3-hydroxypropyl and 3- hydroxy-I-propenyl group at the 3-position in nonpolar organic solvents was discussed.

• Journal of Photoscience
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• v.9 no.2
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• pp.347-349
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• 2002

Synthetic zinc chlorins possessing a hydrophylic polyoxyethylene chain at the 17 -position were prepared. An amphiphilic zinc chlorin possessing a single chIorin moiety showed absorption maxima at 675 nm in an aqueous medium, indicating that the zinc chIorin did not form large aggregates but a dimeric structure. In contrast, amphiphilic zinc chlorin dyads in which two zinc chlorin moieties were connected with a hydrophilic polyoxyethylene linkage showed red-shifted absorption band around 720-740 nm in an aqueous medium. The result indicated that the amphiphilic zinc chlorin dyad self-aggregated to form chlorosome-like oligomer.

• Journal of Photoscience
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• v.9 no.2
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• pp.344-346
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• 2002

Eight intact bacteriochlorophyll (BChl)-d homologs and isomers were isolated from a strain of green sulfur bacterium Chlorobium vibrioforme. All the molecular structures of the BChl-d components were fully determined by a combination of mass spectrometry and $^1$H-NMR spectroscopy. The aggregation behavior of the isomerically pure BChls-d in hydrophobic organic solvents was examined with respect to the stereoisomeric configuration at the C3$^1$ position as well as the bulkiness of the C8 and C12 side-chains by using electronic- absorption spectroscopy.

• Journal of Plant Biology
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• v.33 no.4
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• pp.277-283
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• 1990

Inactivation and reactivation of photosynthetic oxygen evolving complex were studied with isolated spinach (Spinacia oleraceda. L.) photosystem II particles by the activity of oxygen evolution and chlorophyll fluorescence. When the particles were treated with Tris and urea, the oxygen evolution was inactivated and three polypeptides having molecular weights of 33 kDa, 24 kDa and 18 kDa were simultaneously released. But in NaCl-treated particles, two polypeptides of 24 kDa and 18 kDa were removed from PS II particles. The oxygen evolution activities of Tris and urea-treated particles were not restored by adding cation ions (Mg2+, Mn2+ and Ca2+), but the NaCl-treated particles were restored by exogenously added Ca2+. The removal of these extrinsic polypeptides, especially 33 kDa, markedly showed the decrease of the variable fluorescence (Fv). These results are likely to be due to dissipate thermal energy by antenna of photosystem II complexes.