Surface-sensitve spectro-electrochemistry on metalloenzyme electrodes

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K20882
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Bio-related chemistry; Inorganic chemistry
• Research Institution: Hokkaido University
• Principal Investigator: KATO MASARU 北海道大学, 大学院地球環境科学研究院, 准教授 (70709633)
• Research Collaborator: Yagi Ichizo ; Tosha Takehiko
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: タンパク質フィルム電気化学 / 表面増強赤外吸収分光計測 / 金属酵素 / 一酸化窒素還元酵素 / 一酸化窒素

Outline of Final Research Achievements

In this work, we prepared gold electrodes that are active to surface-enhanced infrared absorption (SEIRA) spectroscopy and immobilized a nitric oxide reductase (NOR), which is a trans-membrane metalloenzyme and selectively catalyzes the reduction of nitric oxide (NO) to nitrous oxide (N2O). The NOR electrode showed the electro-catalytic NO reduction activity, indicating that the enzyme was active even on the gold electrode. We also performed SEIRA spectroscopy of the NOR electrode under potential control using carbon monoxide as a vibrational probe. Potential-dependent SEIRA spectra allowed us to determine the redox potentials of the heme and non-heme iron cofactors, which serve as the active site, and then gained the mechanistic insights into the enzymatic NO reduction.

Free Research Field

電気化学

Academic Significance and Societal Importance of the Research Achievements

膜結合型の金属酵素の多くが高い触媒活性を示すことが知られているが，一般的に不安定で容易に失活するためにそれらの電気化学活性評価および表面増強赤外吸収(SEIRA)分光計測の研究例は限られていた．本研究を通して，膜結合型金属酵素の一つである一酸化窒素還元酵素(NOR)を用い，失活することなく電極表面に固定化する方法を確立し，更には，NOR電極の電位制御下でのSEIRA分光計測を実施することで，酵素反応機構の解明が大幅に前進した．本研究で確立した研究手法は他の金属酵素へも適用可能であり，金属酵素が高活性を示す動作原理の解明や高活性な人工電極触媒開発における設計指針を与えてくれるものと考えている．