酵素におけるプロセス性ポリサッカリド転位を駆動する炭水化物-タンパク質の相互作用は,セルロビオヒドローラゼのプロセシビティの計算研究から明らかになった
Brandon C Knott1, Michael F Crowley, Michael E Himmel
1National Bioenergy Center and ‡Biosciences Center, National Renewable Energy Laboratory , Golden, Colorado 80401, United States.
Journal of the American Chemical Society
|May 30, 2014
まとめ
酵素によるセルロースの分解には,2段階のチェーンスレッドメカニズムがあり,速度を制限するステップはチェーントランスロケーションではなく,水解である. 特定のタンパク質の相互作用が,グリコシドヒドロラーゼを通してポリサッカリドの動きを駆動する.
科学分野:
- バイオケミストリー バイオケミストリー
- 構造生物学 構造生物学とは
- 酵素学 酵素学とは
背景:
- タンパク質トンネル経由のポリサッカリドの転位は,グリコシドヒドロラーゼのような酵素に不可欠です.
- 以前の研究は静的結合に焦点を当て,ポリサッカリド鎖のプロセシビティの分子詳細を不明にしてしまった.
研究 の 目的:
- グリコシドヒドローラゼ家族7のセルロビオヒドローラゼのプロセスサイクル中のセルロース鎖転位の分子機構を調査する.
- ポリサッカライド鎖の動きと酵素触媒の作用におけるタンパク質と炭水化物の相互作用の役割を明らかにする.
主な方法:
- セルロース鎖の転位を調べるために分子動力学シミュレーションを使用した.
- チェーンスレッドと水解の自由エネルギーバリアの分析.
- 酵素活性部位内の静電性および芳香性炭水化物の相互作用を調査した.
主要な成果:
- マイケリス複合体を形成するためのチェーンスレッドの2段階メカニズムが特定されました.
- チェーンスレッドの自由エネルギーバリアは,水解バリアよりもかなり低い.
- 保存された極性残留物との静電相互作用が転位を駆動し,芳香的残留物は鎖を導く.
結論:
- 酵素性セルロースの分解は,鎖過程性ではなく,グリコシル化反応によって制限されます.
- 特定の保存された残留物と芳香的相互作用は,グリコシドヒドロラーゼにおける過程的転位に不可欠である.
- この研究は,ポリサッカリドの合成と分解を促進する炭水化物活性酵素の共通のモチーフを明らかにします.
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