Clarification and Control of the Optical Functions of the Reconstituted Light-Harvesting Pigment-Protein Complexes from Purple Photosynthetic Bacteria with Polar Carotenoids

2020 Fiscal Year Final Research Report

• Project/Area Number: 16H04181
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Bio-related chemistry
• Research Institution: Kwansei Gakuin University
• Principal Investigator: Hashimoto Hideki 関西学院大学, 理工学部, 教授 (50222211)
• Project Period (FY): 2016-04-01 – 2021-03-31
• Keywords: 光合成 / アンテナ色素タンパク質複合体 / カロテノイド / 再構成 / 超高速レーザー分光

Outline of Final Research Achievements

Biochemical methods were successfully developed to incorporate various kinds of carotenoid into the photosynthetic membranes or light-harvesting complexes that were prepared from carotenoidless strains of purple photosynthetic bacteria. Steady-state optical absorption, fluorescence excitation and femtosecond to sub-millisecond time-resolved absorption spectroscopies were applied to the carotenoid-reconstituted light-harvesting complexes for the purpose to clarify the exact mechanisms of the excitation energy transfer between carotenoid and bacteriochlorophyll. Highly efficient singlet-singlet excitation energy transfer was realized when the carbonyl containing carotenoids were incorporated into the light-harvesting systems from purple photosynthetic bacteria using the intra-molecular charge transfer (ICT) excited state of the carbonyl containing carotenoids.

Free Research Field

バイオ物質科学

Academic Significance and Societal Importance of the Research Achievements

海洋藻類の光合成アンテナ系では，光学禁制なS1励起状態に共役した分子内電荷移動（ICT）励起状態を発現することで，高効率なエネルギー伝達を実現している。この叡智を紅色光合成細菌の光合成アンテナ系に組み込み，前人未踏の超高効率アンテナ系を創出した点が本研究成果の学術的意義である。本研究成果の社会的意義は，光合成機能を利用した新規光エネルギー変換素子の開発に直結することに留まらず，光産業分野において重要な課題となっている地球資源・環境に適応した太陽光エネルギーの有効利用に関する一定の指針を提示していることである。