システイン結合はテトラヘムタンパク質STCを通過する電子の流れを加速する

Xiuyun Jiang¹, Zdenek Futera¹, Md Ehesan Ali¹

¹Department of Physics and Astronomy, University College London , London WC1E 6BT, U.K.

Journal of the American Chemical Society

|November 10, 2017

まとめ

この研究では,マルチヘムタンパク質の電子伝送率を計算し,システイン結合が電子の流れを 37倍大幅に増加させることを明らかにしました. この発見は生物学的システムにおける電子輸送の理解に不可欠です

科学分野:

バイオ物理学
生物化学
コンピュータ化学

背景:

マルチヘムタンパク質は細胞外電子輸送 (ET) に不可欠である.
ヘム群の間のET速度の定数を決定することは実験的に困難である.
これらの比率を理解することはタンパク質の機能の解明の鍵です

研究の目的:

テトラヘムタンパク質のSTCにおけるヘム-ヘム電子移転 (ET) 速度の定数を理論的に決定する.
ET率の調節におけるシステイン結合の役割を調査する.
生物学的な電子トンネルの洞察を提供するために

主な方法:

電子コップリングの計算のための新しいプロジェクター-オペレータのダイアバティゼーションアプローチを組み合わせた.
分子動力学シミュレーションを使って異星人の自由エネルギーを測定した
ヘム・ヘム理論の速度の定数を計算した

主要な成果:

STCを通る内在の電子流は,下り坂方向 (ヘム1→4) で約3 × 10^6s^-1である.
ヘムペア1~2と3~4のシステイン結合は,電子の流れを約37倍に増加させる.
この増強は,硫黄3p軌道とFe-heme d軌道との混合に起因する.

結論:

トンネリング媒体の原子化と化学的な性質は,短距離での効率的なETに不可欠です.
システイン結合は,マルチヘムタンパク質における電子の流れを著しく改善する.
これらの発見は,MtrCやMtrFのようなタンパク質における電子移転の理解に意味を持つ.

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