Theoretical study on mechanism of proton transfer in photosynthetic proteins based on protein structures

2017 Fiscal Year Final Research Report

• Project/Area Number: 26800224
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Biological physics/Chemical physics/Soft matter physics
• Research Institution: The University of Tokyo
• Principal Investigator: Saito Keisuke 東京大学, 先端科学技術研究センター, 講師 (20514516)
• Project Period (FY): 2014-04-01 – 2018-03-31
• Keywords: 光合成 / プロトン移動 / 水分解 / 量子化学 / 分子動力学 / 水素結合 / 酸解離定数 / 蛋白質

Outline of Final Research Achievements

In photosynthesis of higher plants and algae, the photosystem II (PSII) protein catalyzes a water-splitting reaction where two water molecules are split into one oxygen molecule and four protons by using light energy. We clarified the reaction mechanism of the water-splitting reaction by using quantum chemical calculations. The reaction is composed of four steps. In the first step, one proton is transferred through a water chain near the active site (the Mn4CaO5 cluster) of PSII. In the third step, other proton is transferred via the asparagine side chain (D1-Asp61) located at the vicinity of the Mn4CaO5 cluster. The remaining protons are released when turning over from the fourth step to the first step.

Free Research Field

生物物理学理論