Moorella thermoaceticaeticaからのコリノイド/鉄硫黄タンパク質のスペクトロスコーピック研究

Troy A Stich¹, Javier Seravalli, Swarnalatha Venkateshrao

¹Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.

Journal of the American Chemical Society

|April 13, 2006

まとめ

コルリノイド鉄硫黄タンパク質 (CFeSP) は,軸性水結合体を利用し,Co-OH2結合を延長する. この改変により,無酸素微生物におけるメチル転移に不可欠な,異解性Co-C結合の割れが容易になる.

科学分野:

バイオケミストリーバイオケミストリー
バイオ・オーガニック化学バイオ・オーガニック化学
微生物の代謝について

背景:

メチル転移反応は,多くの生化学的経路において不可欠である.
コバラミン依存メチルトランスフェラーゼは,コバルトコファクターを使用してメチル群の転送を促進します.
コバラミンの軸性結合は,Co-C結合の割れメカニズムと割れ速度に影響する.

研究の目的:

コリノイド鉄硫黄タンパク質 (CFeSP) のコリノイドコファクターの軸結合を調査する.
CFeSPが無酸素微生物におけるメチル転送をどのように促進するのかを理解する.
ヘテロリティックなCo-C結合割れの構造的基礎を解明する.

主な方法:

共振ラーマン光譜法
マグネティック・サークラル・ダイクロイズム (MCD) スペクトロスコピー
電子パラマグネティック共振 (EPR) スペクトロスコピー
計算化学はコンピュータ化学である.

主要な成果:

CFeSPのMe-Co3+およびCo2+状態は,自由コバラミン共因子に類似する軸性水結合体を持っています.
タンパク質に結合したコファクターにおけるCo-OH2結合の長さは,自由コファクターと比較して約0.2アングストーム長くなっています.
この結合延長は,コバルトの中心をより"Co1+のような"ものにすることを提案しています.

結論:

CFeSPの軸性水リンガンドは,コバルト中心の電子特性を調節する上で重要な役割を果たします.
延長されたCo-OH2結合は,メチル移転に不可欠なヘテロリティックなCo-C結合の割れ方を容易にします.
この研究は,エネルギー生成と無酸素微生物による炭素合成におけるメチル転送のメカニズムに関する構造的洞察を提供します.

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