モノジンクβ-ラクトマゼの水補助反応機構

Matteo Dal Peraro¹, Leticia I Llarrull, Ursula Rothlisberger

¹International School for Advanced Studies, SISSA-ISAS, INFM-Democritos Center, via Beirut 4, 34014 Trieste, Italy.

Journal of the American Chemical Society

|September 30, 2004

まとめ

ハイブリッド・カー・パーリネッロのQM/MM計算により,触媒性水分子が発見された.

科学分野:

バイオケミストリーバイオケミストリー
コンピューティング・ケミストリー
酵素学酵素学とは

背景:

ベータ・ラクタマゼは,ベータ・ラクタム系抗生物質を水分解する酵素です.
バシルス・セレウスのモノジンクβ-ラクタマゼ (BcII) は,抗生物質耐性における重要な酵素である.
BcIIの触媒メカニズムを理解することは,新しい抗生物質の開発に不可欠です.

研究の目的:

セフォタキシムをバチルス・セレウス・モノジンク・ベータ・ラクトマゼ (BcII) によって水解する反応機構を解明する.
触媒過程におけるアクティブサイト水分子の役割を調査する.
他のベータ・ラクタム基板に対する提案されたメカニズムの汎用性を決定する.

主な方法:

ハイブリッドカー-パーリネッロ量子力学/分子力学 (QM/MM) の計算を用いた.
この研究は,BcII.IIによるセフォタキシムの水解に重点を置いた.
反応経路と自由エネルギーの障壁が計算されました.

主要な成果:

触媒性水分子は,亜鉛イオンと結合し,陽子の移転を促進することによって,基本的な役割を果たします.
保存された水素結合ネットワーク (Asp120,Cys221,His263) は,核愛者を指向し,第2の水分子を誘導する.
計算された自由エネルギーバリアは実験データと一致しており,メカニズムは様々なβ-ラクトーム基板に対して一般的と思われる.

結論:

この研究は,BcII触媒によるセフォタキシム水解のための詳細なQM/MMベースのメカニズムを提供します.
アクティブサイトの水分子と水素結合ネットワークは,触媒作用に不可欠です.
この発見は,β-ラクタマゼの保存された触媒戦略を示唆している.

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