Operando vibrational spectroscopic measurements at metalloenzyme-modified electrodes toward developments of bio-inspired electrocatalysts

2021 Fiscal Year Final Research Report

• Project/Area Number: 19H02664
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 32010:Fundamental physical chemistry-related
• Research Institution: Hokkaido University
• Principal Investigator: Yagi Ichizo 北海道大学, 地球環境科学研究院, 教授 (40292776)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 金属酵素 / 脂質二重膜 / 一酸化窒素還元酵素 / チトクロムc酸化酵素 / 電極触媒反応 / 表面増強赤外吸収分光法 / 人工生体膜モデル

Outline of Final Research Achievements

To design bio-inspired electrocatalysts, metalloenzymes were buried in the artificial bilayer lipid membrane (BLM) systems constructed on electrode surfaces combined with surface enhanced infrared absorption (SEIRA) spectroscopy. The targets are the cytochrome c-dependent nitric oxide reductase (cNOR) in the denitrification system and cytochrome c oxidase (CcO) in the respiration chain. Enzyme reactions at the both systems were monitored by electrochemical vibrational spectroscopic measurements.
At the cNOR system, the orientation of the fixed enzymes were controlled by changing the ratio of end groups and chain lengths of the self-assembled monolayer on the electrode surfaces. Furthermore, the more stable BLMs were constructed, enabling us to observe the intermediate NO vibrational bands during the reaction. At the CcO system, the effect of the adsorption of cytochrome c on CcO was evaluated.

Free Research Field

界面物理化学、電極触媒

Academic Significance and Societal Importance of the Research Achievements

金属酵素などの活性中心を模倣する生体模倣電極触媒は、従来、白金等の遷移金属ベースで発展してきた燃料電池電極触媒や硝酸還元触媒の限界を打ち破る触媒設計指針として研究されてきた。しかしながら、反応時の金属酵素の活性中心の反応中間体吸着構造やその周辺の配位構造の影響については未だ未解明であり、今回SEIRA活性基板上に構築した人工生体膜モデルで反応を駆動しながら、酵素の内部構造や反応中間体を捉える手法が確立できた。特にcNORは、地球温暖化ガスとして注目されている亜酸化窒素(N2O)を生成する反応であり、その生成機構を解明し、抑制することにつながるため、社会的にも意義のある研究につながった。