ハンマーヘッドリボ酵素の冷凍デナチュレーション

Peter J Mikulecky¹, Andrew L Feig

¹Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, USA.

Journal of the American Chemical Society

|February 7, 2002

まとめ

核酸ではこれまで観察されていなかった冷変異は,ハンマーヘッドリボ酵素で実証されました. この発見は,RNAとDNAの折り畳みの熱力学における熱容量差の重要性を強調しています.

科学分野:

バイオケミストリーバイオケミストリー
熱力学は熱力学である.
分子生物学は分子生物学である.

背景:

寒冷デナチュレーションは,タンパク質における熱力学的現象であり,折りたたまれた状態と開いた状態の熱容量差に起因する.
この現象は,核酸の軽微な折り畳み熱容量 (DeltaCp) により,核酸には存在しないと考えられていた.

研究の目的:

核酸の寒冷無性化の可能性を調査する.
ハンマーヘッドリボ酵素の低温構造的振る舞いを決定するために.

主な方法:

円形二重化スペクトロスコピーは,異なる温度と条件下でハンマーヘッドリボジームの構造を分析するために使用されました.
データは熱力学パラメータを計算するために2つの状態モデルに組み込まれました.

主要な成果:

ハンマーヘッドリボ酵素の寒い展開は,−20°Cで観察され,三次構造の喪失を示した.
熱と冷の両方の展開は, 53°C と -1°C の移行温度 (Tm) の特定の条件下で発生しました.
計算したDeltaCpは3.4kJ mol-1 K-1で,DNA二重複の値と一致した.

結論:

この研究は,核酸における冷変変異の直接的な証拠を初めて提供している.
この発見は,核酸折り畳みの熱力学におけるDeltaCpの重要な役割を強調し,以前の仮定に異議を唱える.

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