Functional and Structural Characterization of Electron Transfer Reactions in Mitochondria Respiratory Chain Utilizing Nanodisc

2015 Fiscal Year Final Research Report

• Project/Area Number: 25288072
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Bio-related chemistry
• Research Institution: Hokkaido University
• Principal Investigator: Ishimori Koichiro 北海道大学, 理学(系)研究科(研究院), 教授 (20192487)
• Co-Investigator(Kenkyū-buntansha): Takeshi Uchida 北海道大学, 大学院理学研究院, 准教授 (30343742) ; Tomohide Saio 北海道大学, 大学院理学研究院, 助教 (80740802)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: シトクロムc酸化酵素 / シトクロムc / ナノディスク / 電子伝達反応 / ヘム / MSP / ドッキングシミュレーション / 構造揺らぎ

Outline of Final Research Achievements

We reconstituted cytochrome c oxidase (CcO) into a biomembrane model, nanodisc, to characterize its functions in the absence of detergents. The resonance Raman spectra revealed that the reconstitution of CcO into the nanodisc increases the oxygen affinity, leading to efficient reduction of dioxygen to water molecules. To discuss interactions regulating the electron transfer (ET) reactions, we examined the cytochrome c (Cyt c) interaction site on CcO by docking simulation. Unexpectedly, electrostatic interactions do not contribute to the stabilization of the complex, but regulate the binding orientation of Cyt c on CcO. Instead, hydrophobic interactions are the primary factors to stabilize the complex, and the dehydration associated with the formation of the hydrophobic interactions is the key process to facilitate the complex formation. On the other hand, the structural fluctuations are suppressed in the CcO interaction site on Cyt c, which would also characterize the ET reaction.

Free Research Field

生物無機化学