Study on the Principle of Photosynthetic Light Energy Conversion Based on Divergence of Chlorophyll Molecules

The composition of photosystem II (PSII) in the chlorophyll (Chl) d-dominatedcyanobacterium Acaryochloris marina MBIC 11017 was investigated to enhance the generalunderstanding of the energetics of the PSII reaction center. We first purifiedphotochemically active complexes consisting of a 47 kDa chlorophyll protein (CP47), CP43’(PcbC), D1, D2, cytochrome b559, PsbI, and an unknown small polypeptide. The pigmentcomposition per two pheophytin (Phe) a molecules was 55 ± 7 Chl d, 3.0 ± 0.4 Chl a, 17 ± 3α-carotene, and 1.4 ± 0.2 plastoquinone-9. A special pair was detected by a reversibleabsorption change at 713 nm (P713) together with a cation radical band at 842 nm. FTIRdifference spectra of the specific bands of a 3-formyl group allowed assignment of the specialpair. The combined results indicate that the special pair includes a Chl d homodimer.The primary electron acceptor was shown by photoaccumulation to be Phe a, and itspotential was shifted to a higher value than that in the Chl a/Phe a system. The overallenergetics of PSII in the Chl d system adapt to changes in the redox potentials, with P713as the special pair utilizing lower light energy at 713 nm. Our findings support the ideathat changes in photosynthetic pigments combine with modification of the redox potentialsof electron transfer components to give rise to energy changes in the total reaction system.■原 著■ 2007 年度神奈川大学総合理学研究所共同研究助成論

22. A New Technique for the Group Velocity Analysis of Dispersive Seismic Waves

A new technique of high resolution group velocity analysis for the study of dispersive seismic surface waves ,is proposed. This method comprises the development of the Instantaneous Frequency Analysis which has a basis in the Maximum Entropy Spectral Analysis. The feasibility of this method is tested using synthetic seismograms. Particular attention is paid from the practical point of view to the optimum length of the linear prediction filter and the resolution to the interference of the fundamental mode and the higher mode. We compare this method with a conventional bandpass filtration technique using the same synthetic seismograms. Our results show that this method has the advantage of retrieving the higher mode group velocity even for shallow earthquakes.表面波の分散を研究するための,高精度の群速度推定法を考察した.この方法は最大エントロピー法を基礎とする,瞬間周波数解析に基づいている.この方法の有効性を理論記象を用いて調べ,特に実用的観点から,予測フィルターの最適な長さ及び基本モードと高次モードの干渉に対する分解能に注意をはらった.さらにバソドパスフィルターによる方法と比較した.この新しい方法は震源の浅い地震で励起された高次モードの群速度をも推定できる点で従来の方法に優っている