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Ki-Seok Yoon Last modified date:2021.10.29

Associate Professor / Department of Chemistry and Biochemistry
International Institute for Carbon-Neutral Energy Research

Undergraduate School
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Academic Degree
Ph.D. (The University of Tokyo)
Country of degree conferring institution (Overseas)
Field of Specialization
Biotechnology, Applied Microbiology, Enzyme Technology, Biochemistry
Total Priod of education and research career in the foreign country
Research Interests
  • Development of novel biocatalysts involved in H2 activation, CO2 conversion, O2 activation, N2 fixation, and water-splitting reaction
    keyword : hydrogenase, CO2 fixing enzyme, photosynthetic water-oxidation, N2 fixation
Academic Activities
1. Takuo Minato, Takamasa Teramoto, Naruhiko Adachi, Nguyen Khac Hung, Kaho Yamada, Masato Kawasaki, Masato Akutsu, Toshio Moriya, Toshiya Senda, Seiji Ogo, Yoshimitsu Kakuta, Ki-Seok Yoon, Non-conventional Octameric Structure of C-phycocyanin, Communications Biology, 2021.11, C-phycocyanin (CPC), a blue pigment protein, is an indispensable component of giant phycobilisomes, which are light-harvesting antenna complexes in cyanobacteria that transfer energy efficiently to photosystems I and II. X-ray crystallographic and electron microscopy (EM) analyses have revealed the structure of CPC to be a closed toroidal hexamer by assembling two trimers. In this study, the structural characterization of non-conventional octameric CPC is reported for the first time. Analyses of the crystal and cryogenic EM structures of the native CPC from filamentous thermophilic cyanobacterium Thermoleptolyngbya sp. O-77 unexpectedly illustrated the coexistence of conventional hexamer and novel octamer. In addition, an unusual dimeric state, observed via analytical ultracentrifugation, was postulated to be a key intermediate structure in the assemble of the previously unobserved octamer. These observations provide new insights into the assembly processes of CPCs and the mechanism of energy transfer in the light-harvesting complexes..
2. Ogo, Seiji; Kishima, Takahiro; Yatabe, Takeshi; Miyazawa, Keishi; Yamasaki, Ryunosuke; Matsumoto, Takahiro; Ando, Tatsuya; Kikkawa, Mitsuhiro; Isegawa, Miho; Yoon, Ki-Seok; Hayami, Shinya, [NiFe], [FeFe], and [Fe] Hydrogenase Models from Isomers, Sci. Adv. , 6, eaaz8181, 2020.06, The study of hydrogenase enzymes (H2ases) is necessary because of their importance to a future hydrogen energy
economy. These enzymes come in three distinct classes: [NiFe] H2ases, which have a propensity toward H2 oxidation;
[FeFe] H2ases, which have a propensity toward H2 evolution; and [Fe] H2ases, which catalyze H− transfer. Modeling
these enzymes has so far treated them as different species, which is understandable given the different cores and
ligand sets of the natural molecules. Here, we demonstrate, using x-ray analysis and nuclear magnetic resonance,
infrared, Mössbauer spectroscopies, and electrochemical measurement, that the catalytic properties of all three
enzymes can be mimicked with only three isomers of the same NiFe complex..