Oxygen generation mechanism is elucidated first in the
world.
Prof. Nobuo Kamiya, Osaka City University, successfully elucidated exact chemical
compositions and atom arrangements of the metal-oxygen cluster in
the photosynthesis process of a plant (April 2012) .
The elucidation of this oxygen generation mechanism is the first in the
world.
The successful study result will accelerate development of the
artificial photosynthesis and greatly contribute to the solutions to energy,
environment and food issues. *Osaka City University: http://www.osaka-cu.ac.jp/ja
In the plant’s photosynthesis process, two photosystems operate: a
photosystem I (PSI) to reduce carbon dioxide gas and a photosystem II (PSII) to
generate oxygen. It has been said that
the oxygen generation reaction is performed in the metal-oxygen clusters
of the PSII.
The overall structure of the PSII is illustrated in Fig. 1. As illustrated, the PSII is a compound
consisting of two monomers. The PSII
receives sunlight and splits water to generate oxygen molecules and at the same
time to release electrons.
The electrons are used to transform carbon dioxide into
glucose.
In the compound structure, the oxygen generation centers are located
at two encircled positions.
Fig. 1 Overall structure of PSII compound
It has been said
that PSII oxygen generation reaction progresses in the metal-oxygen
cluster in which four manganese atoms (Mn) and one calcium atom (C) are coupled
together by a plurality of oxygen atoms (O).
No one has known exact chemical compositions and atom arrangements
of the metal-oxygen cluster, however.
Fig. 2 Chemical structure of oxygen generation
center
Purple: Manganese atoms
Yellow: Calcium atom
Red: Oxygen atoms coupling metal atoms together
Orange: Water Oxygen atoms
Co-Sponsors:
* Institute for Integrated Cell-Material Sciences (iCeMS), Kyoto University
* Strategic International Research Cooperative Program (Finland-Japan), JST
* Academy of Finland
