ヒストンライシンメチルトランスフェラーゼSET7/9の触媒機構と製品特異性:複数の初期構造を持つab initio QM/MM-FE研究
1Department of Chemistry, New York University, New York 10003, USA.
Journal of the American Chemical Society
|January 26, 2006
まとめ
ヒストンライシンメチレーションは遺伝子活動を調節する. SET7/9酵素は,S(N) 2反応を介してこれを触媒化し,特異性は,二メチル化接近攻撃形状を防止することによって達成されます.
科学分野:
- バイオケミストリー バイオケミストリー
- 分子生物学は分子生物学である.
- コンピューティング・ケミストリー
背景:
- ヒストンライシンメチレーションは,クロマチンの構造と遺伝子発現を調節する重要なエピジェネティックメカニズムです.
- ヒストンメチルトランスファーゼの反応機構と特異性を理解することは,遺伝子調節を解読する上で極めて重要です.
研究 の 目的:
- ヒストンライシンメチルトランスフェラーゼSET7/9.9の反応機構と製品特異性を調査する.
- 計算方法を用いた触媒プロセスの理論的理解を提供すること.
主な方法:
- Ab initio量子力学/分子力学自由エネルギー (QM/MM-FE) の計算.
- SET7/9酵素を研究するために,分子ダイナミクスシミュレーションを使用しました.
- 自由エネルギーの障壁は,MP2 ((6-31+G) QM/MMレベルで計算されました.
主要な成果:
- SET7/9によって触媒化されたメチル転移反応は,線内S(N) 2核性置換機構に従っている.
- 70%の解離的性質を持つ移行状態が特定されました.
- 計算された自由エネルギーバリア (20.4 +/- 1.1 kcal/mol) は,実験的な推定値 (20.9 kcal/mol) とほぼ一致しています.
- バリアの変動は,核愛性の攻撃距離と攻撃角度と相関しています.
- SET7/9のモノメチルトランスフェラーゼ特異性は,二メチル化のために破壊された接近攻撃形状に起因する.
結論:
- この研究は,SET7/9の詳細な反応機構を明らかにし,そのS(N) 2性質を確認した.
- 計算上の発見は,酵素の触媒バリアに関する実験的観測を裏付けている.
- モノメチルトランスフェラーゼとしてのSET7/9の製品特異性のメカニズムは,構成制御によって説明されています.
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