Abstract
Development of efficient artificial photosynthetic systems is crucial to address the energy and environmental problems that mankind faces. Construction of artificial photosynthesis utilizing natural photosynthetic proteins has been an attractive approach because of their high quantum efficiencies. In this study, we have generated photosystem II (PSII)-gold nanoparticle conjugate aiming at development of light-driven water-splitting nanodevice. PSII core complexes from the thermophilic cyanobacterium T. elongatus, in which a His-tag was introduced to the C-terminus of CP47, were bound to gold nanoparticles (20 nm diameter) via Ni-NTA. The absorbance of the Chl Qy band of PSII (674 nm) relative to that of the plasmon absorption of gold nanoparticles (530 nm) exhibited that approximately four PSII dimers are bound to a single nanoparticle. Binding of PSII to a gold nanoparticle was also demonstrated by TEM analysis. The PSII on gold nanoparticles retained ~26% activity of O2 evolution relative to control PSII. The obtained PSII-gold nanoparticle conjugate will be a useful devise in the development of a light-energy conversion nanosystem utilizing electrons from water.
