Rieske プロトンポンプの電荷調節ゼロ,ワン,ツープロトン結合電子転送

Jordan C Koone¹, Mikaela Simmang², Devin L Saenger²

¹Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76706, United States.

Journal of the American Chemical Society

|July 24, 2023

まとめ

研究者は,リスケタンパク質の電子移転 (ΔZ_ET) 中の純電荷変化を定量化した. 彼らは,電子伝送 (ET),陽子結合電子伝送 (PCET),および2陽子結合電子伝送 (2PCET) メカニズムをサポートする異なる電荷状態を発見した.

科学分野:

生物化学
バイオエネルギー
タンパク質の電気化学

背景:

タンパク質の電子移転 (ΔZ_ET) 中の純電荷変化を測定することは困難である.
ΔZ_ET値は,電子伝送 (ET) と陽子結合電子伝送 (PCET) のメカニズムを理解するために重要である.
Rieske [2Fe-2S] タンパク質は,生物学的電子輸送鎖の重要な構成要素である.

研究の目的:

電子移転 (ΔZ_ET) 中の陽子ポンプによる純電荷調節の度合いを決定する.
リスケタンパク質における電子移転 (ET) と陽子結合電子移転 (PCET) を区別する.
Rieske [2Fe-2S]サブユニットでプロトンポンプのpH依存メカニズムを調査する.

主な方法:

"サーマス・サーモフィルス" (trunc*Tt*Rp) のリースケ [2Fe-2S]サブユニットからのタンパク質"充電梯"の合成.
pH値の範囲でΔZ_ETの120の静電測定を行った.
陽子エネルギーとΔZ_ET値と相関する酸化還元電位.

主要な成果:

pH 6.0で,trunc*Tt*Rpは単一のETと一致する - 1. 01 ± 0. 14のΔZ_ETを示した.
pH 8. 8で,trunc*Tt*Rpは,PCETを示す - 0. 01 ± 0. 45のアイソ電気 ΔZ_ETを示した.
pH 10.6 で,trunc*Tt*Rp は ΔZ_ET を +1.37 ± 0.60 と示し,これは 2 プロトン結合ET (2PCET) と一致する.
観測されたΔZ_ETの変化は,ヒスティディンH154およびH134のプロトネーションに起因した.

結論:

この研究は,pHの範囲でリースケタンパク質の直接電気静的測定 (ΔZ_ET) を提供している.
発見は,Rieskeタンパク質のFe-調整ヒスティディンを含む離散型陽子ポンプメカニズムを支持する.
トランク*Tt*RpにおけるET,PCET,および2PCETメカニズム間のpH依存の移行が実証された.

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