形成に結合するE. coliペプチド変形酵素の構造:Fe2+がZn2+よりもFe2+を活性サイト金属として好むという洞察
Rinku Jain1, Bing Hao, Ren-Peng Liu
1Departments of Biochemistry and Chemistry, and Ohio State Biophysics Program, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA.
Journal of the American Chemical Society
|March 31, 2005
まとめ
鉄は,E. coliペプチド変形酵素 (PDF) の活性に好ましい金属である. 構造研究は鉄を明らかにする.
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:
- E. coliペプチド変形酵素 (PDF) は,新たに合成されたタンパク質からN端の形式基を除去します.
- PDFは当初,亜鉛依存酵素であると信じられていたが,鉄が活性金属であることを研究が示している.
- 金属の好みを理解することは,PDFの触媒メカニズムと機能を明らかにするために不可欠です.
研究 の 目的:
- E. coli PDFの異常な金属嗜好の構造的根拠を調査する.
- 変型化産物であるホルマートの鉄 (Fe-PDF),コバルト (Co-PDF),亜鉛 (Zn-PDF) 形態への結合を比較する.
- 構造的差異と酵素活性における観察された差異を相関させる.
主な方法:
- 高解像度のX線結晶学を用いて,Fe,Co,Zn-PDFの構造を決定した.
- 各酵素の構造は,変型化の産物であるフォーマットとの複合体で得られた.
- 金属-リガンド相互作用とフォーマット結合モードの分析.
主要な成果:
- フォーマートは,活性サイト金属と3つの酵素形態とも結合し,特定のアミノ酸残留物 (Leu91, Gln50, Glu133) と相互作用する.
- フォーマット結合における重要な違いは,Fe-PDFとCo-PDFにおけるバイデント酸結合と,Zn-PDFにおけるモノデント酸結合である.
- これらの構造的変異は,異なる金属に関連する異なる触媒活動の洞察を提供します.
結論:
- 構造データは,PDFの金属依存性活動差を説明する最初の証拠を提供します.
- 鉄がホルミール群の分裂のための移行状態を結合し活性化する優れた能力は,Fe-PDFのより高い活性化の原因である可能性が高い.
- この研究は,PDFの触媒機構と金属イオン協調の理解を前進させます.
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