TY - JOUR
T1 - Amphiphilic zinc bacteriochlorophyll a derivatives that function as artificial energy acceptors in photosynthetic antenna complexes chlorosomes of the green sulfur photosynthetic bacterium Chlorobaculum limnaeum
AU - Saga, Yoshitaka
AU - Takahashi, Naoya
AU - Miyatake, Tomohiro
AU - Tamiaki, Hitoshi
PY - 2018/2/15
Y1 - 2018/2/15
N2 - Green photosynthetic bacteria have extramembranous light-harvesting complexes called chlorosomes. Light-energy captured by bacteriochlorophyll (BChl) self-aggregates inside chlorosomes is transferred to BChl a-peptide complexes called baseplates on the chlorosome surface. We substitute the baseplate complex in chlorosomes from a green sulfur photosynthetic bacterium Chlorobaculum limnaeum with amphiphilic Zn BChl a derivatives. Zn BChl a derivatives 1–3, which were esterified with polyethylene glycol (PEG) 600, PEG400, and diethylene glycol, respectively, were successfully hybridized with chlorosomes without baseplates. These derivatives in the hybridized chlorosomes emitted by predominant excitation of BChl e self-aggregates at 460 nm, indicating that they were able to accept the excitation energy from BChl e aggregates inside chlorosomes. Zn BChl a derivatives 1 and 2 emitted at 787 nm by the excitation energy transfer. In contrast, fluorescence from 3 esterified with a short hydrophilic chain, diethylene glycol, was broadened around 785 and 820 nm. The broad emission bands would consist of at least two bands, which were ascribable to the monomeric and aggregated forms. These results indicate that PEG600 and PEG400 provide appropriate amphiphilicity to Zn BChl a derivatives for dispersion in the membranous region of chlorosomes. The present study will be helpful for not only elucidation of the energy transfer mechanism in chlorosomes but also development of artificial photofunctional supramolecular complexes by hybridization of natural photosynthetic systems with synthetic molecules.
AB - Green photosynthetic bacteria have extramembranous light-harvesting complexes called chlorosomes. Light-energy captured by bacteriochlorophyll (BChl) self-aggregates inside chlorosomes is transferred to BChl a-peptide complexes called baseplates on the chlorosome surface. We substitute the baseplate complex in chlorosomes from a green sulfur photosynthetic bacterium Chlorobaculum limnaeum with amphiphilic Zn BChl a derivatives. Zn BChl a derivatives 1–3, which were esterified with polyethylene glycol (PEG) 600, PEG400, and diethylene glycol, respectively, were successfully hybridized with chlorosomes without baseplates. These derivatives in the hybridized chlorosomes emitted by predominant excitation of BChl e self-aggregates at 460 nm, indicating that they were able to accept the excitation energy from BChl e aggregates inside chlorosomes. Zn BChl a derivatives 1 and 2 emitted at 787 nm by the excitation energy transfer. In contrast, fluorescence from 3 esterified with a short hydrophilic chain, diethylene glycol, was broadened around 785 and 820 nm. The broad emission bands would consist of at least two bands, which were ascribable to the monomeric and aggregated forms. These results indicate that PEG600 and PEG400 provide appropriate amphiphilicity to Zn BChl a derivatives for dispersion in the membranous region of chlorosomes. The present study will be helpful for not only elucidation of the energy transfer mechanism in chlorosomes but also development of artificial photofunctional supramolecular complexes by hybridization of natural photosynthetic systems with synthetic molecules.
KW - Bacteriochlorophyll
KW - Chlorosome
KW - Green photosynthetic bacteria
KW - Photosynthesis
KW - Reconstitution
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U2 - 10.1016/j.jphotochem.2017.08.001
DO - 10.1016/j.jphotochem.2017.08.001
M3 - Article
AN - SCOPUS:85028333742
VL - 353
SP - 612
EP - 617
JO - Journal of Photochemistry and Photobiology A. Chemistry
JF - Journal of Photochemistry and Photobiology A. Chemistry
SN - 1010-6030
ER -