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ハンマーヘッドリボジームにおける一般酸触媒を検知する
Jason M Thomas1, David M Perrin
1Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, B.C., Canada, V6T 1Z1.
Journal of the American Chemical Society
|January 22, 2009
まとめ
二重金属カチオン (M(2+)) と特定のリボ酵素群は,ハンマーヘッドリボ酵素の一般的な酸触媒に不可欠です. この研究は,M2+) -コファクター協調がG8 2'-OH pKを低下させることを示し,それらの役割を明確にしています.
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.
- 酵素学 酵素学とは
背景:
- ハンマーヘッドリボ酵素は,触媒的な核を持つRNA酵素である.
- 最近の研究では,特定のリボ酵素群と金属イオンが触媒に関与することを示唆しています.
- ハンマーヘッドリボ酵素における二価金属カチオン (M(2+)) の正確な触媒的役割は不明である.
研究 の 目的:
- S.マンソニのハンマーヘッドリボ酵素における一般的酸触媒機構の機能的特徴を明らかにする.
- この触媒過程における共因子としての二価金属カチオン (M(2+)) の役割を明らかにする.
- G8 2 extquotesingle-OHリボジーム残基が一般酸性触媒に与える寄与を調査する.
主な方法:
- ハンマーヘッドリボジームが天然のリボ・フォスフォディエステルとブリッジング-5エクストクォーテス・シングル・フォスフォロチオート基板に分裂する比較分析.
- G8 2 extquotesingle-OHリボジーム残基のサイト指向型変異.
- 二価金属カチオン (M(2+)) コファクターの置換.
- 放射性標識のブリッジング-5エクストクォーテスシングル-フォスフォロチオート基板の合成.
主要な成果:
- 自然基質の割れは,G8 2 extquotesingle-OH変異とM(2+) コファクターの存在/同一性によって抑制されました.
- フォスフォロチオート基板の裂け方は,これらの修正に無感であった.
- 一般的な酸 pK (a) 干渉は,M (a) 2+) 置換とG8 2 extquotesingle-OH修正で観察されました.
結論:
- M(2+) コファクターとG8 2エクストクォーテシングル-OHの両方が,ハンマーヘッドリボ酵素の一般酸触媒に不可欠である.
- M(2+) コファクターは,ルイス酸の相互作用によって離脱群を安定させない.
- 移行状態のM(2+) G8の2 extquotesingle-OHの調整は,おそらくpK(aを低下させ,離脱グループへの陽子の移転を強化する.
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