ディエルス-アルデラーゼリボエンザイムにおけるマグネシウム依存活性部位構成選択

Tomasz Bereźniak¹, Maï Zahran, Petra Imhof

¹Computational Molecular Biophysics, IWR, University of Heidelberg, Im Neuenheimer Feld 368, 69120 Heidelberg, Germany.

Journal of the American Chemical Society

|August 21, 2010

まとめ

マグネシウムイオンは,触媒性RNA分子であるダイエルス-アルデラーゼリボ酵素の活性構成を安定させます. 高濃度のマグネシウムは,リボ酵素にとって極めて重要です.

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:

Diels-Alderaseリボ酵素は,Diels-Alder反応を触媒化する,in vitroで進化したRNA酵素である.
これらの反応は,有機合成に不可欠な炭素-炭素結合を形成する.
その触媒メカニズムを理解することは,その可能性を活用する鍵です.

研究の目的:

ディエルス-アルデラーゼリボ酵素の構造的動態を調べるために.
マグネシウムイオンの触媒活性における役割を明らかにする.
リボ酵素の機能がMg2+) 濃度に依存していることを説明する.

主な方法:

分子動力学 (MD) シミュレーションを行いました.
シミュレーションは結晶環境と水性環境の両方で実施されました.
異なるMg2+) イオン濃度の影響を分析した.

主要な成果:

リボ酵素の触媒ポケットは非常にダイナミックです.
低濃度 (Mg2+) の場合,不活性で閉じた状態が優勢である.
高濃度のMg2+ (例えば54mM) は,活発で開いた状態を安定させる.
カチオンは特定のリン酸部位に結合し,ポケットを開くことを容易にします.
自由エネルギープロファイルは,高Mg2+) レベルでのポケット開口に対するバリアが低いことを示しています.

結論:

マグネシウムイオンは,ダイエルス-アルデラーゼリボ酵素の触媒的に活性な構成を安定させるために重要である.
Mg2+) の濃度は,リボエンザイムが開いた活性状態をとる能力に直接影響を及ぼします.
これらの発見は,実験的に観察されたMg2+依存活性に対する構造的基礎を提供する.

さらに関連する動画

09:30

Modeling Ligands into Maps Derived from Electron Cryomicroscopy

Published on: July 19, 2024

15:05

Deciphering the Structural Effects of Activating EGFR Somatic Mutations with Molecular Dynamics Simulation

Published on: May 20, 2020

関連する概念動画

01:19

Allosteric Proteins-ATCase

Binding sites linkages can regulate a protein's function. For example, enzyme activity is often regulated through a feedback mechanism where the end product of the biochemical process serves as an inhibitor.
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis pathway,...

00:49

Ligand Binding and Linkage

Allosteric proteins have more than one ligand binding site; the binding of a ligand to any of these sites influences the binding of ligands to the other sites. When a protein is allosteric, its binding sites are called coupled or linked. In the case of enzymes, the site that binds to the substrate is known as the active site and the other site is known as the regulatory site. When a ligand binds to the regulatory site, this leads to conformational changes in the protein that can influence the...

01:13

Introduction to Mechanisms of Enzyme Catalysis

For many years, scientists thought that enzyme-substrate binding took place in a simple "lock-and-key" fashion. This model stated that the enzyme and substrate fit together perfectly in one instantaneous step. However, current research supports a more refined view scientists call induced fit. The induced-fit model expands upon the lock-and-key model by describing a more dynamic interaction between enzyme and substrate. As the enzyme and substrate come together, their interaction causes a mild...

01:13

Induced-fit Model

Most chemical reactions in cells require enzymes—biological catalysts that speed up the reaction without being consumed or permanently changed. They reduce the activation energy needed to convert the reactants into products. Enzymes are proteins, that usually work by binding to a substrate—a reactant molecule that they act upon.
Enzymes exhibit substrate specificity, meaning that they can only bind to certain substrates. This is mainly determined by the shape and chemical characteristics of...

02:40

Ligand Binding Sites

Proteins are dynamic macromolecules that carry out a wide variety of essential processes; however, the activities of most proteins depend on their interactions with other molecules or ions, known as ligands.
Protein-ligand interactions are quite specific; even though numerous potential ligands surround a cellular protein at any given time, only a particular ligand can bind to that protein. Moreover, a ligand binds only to a dedicated area on the surface of the protein, known as the...