アリファティックハロゲナーゼ,SyrB2における反応結果と基板位置の実験的相関
Ryan J Martinie1, Jovan Livada1, Wei-chen Chang1
1Departments of †Chemistry and of ‡Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.
Journal of the American Chemical Society
|May 13, 2015
まとめ
鉄 (II) -および2 - (オクソ) グルータレート依存 (Fe/2OG) 酸化酵素は,さまざまな反応性を示しています. 鉄の中心付近の基質の位置が,SyrB2のヒドロキシラートかクロリナートかを決定し,酵素の結果を説明する.
科学分野:
- バイオケミストリー バイオケミストリー
- 酵素学 酵素学とは
- 構造生物学 構造生物学とは
背景:
- 鉄 (II) -および2 - (オクソ) グルータレート依存 (Fe/2OG) オキシゲナーゼは,様々な化学反応を行います.
- この酵素ファミリーにおける基板特異性と反応結果の決定を理解することは,依然として課題です.
- Fe/2OGハロゲナーゼSyrB2は,アミノ酸基板によって異なる塩素化および水酸化活動を示しています.
研究 の 目的:
- 基板の位置がFe/2OG酸素酵素 SyrB2.2.の反応結果にどのように影響するか調査する.
- 基板の炭素位置と観察された塩素化と水酸化を相関させるため.
- 他のFe/2OG酸素酵素酵素における結果を予測するための枠組みを提供する.
主な方法:
- 電子パラマグネティック共振 (EPR) スペクトロスコーピーを利用して,SyrB2.2の鉄-ニトロシル添加物を研究しました.
- 基質デウテリウム原子と鉄-ニトロシル種間の超細い結合を測定した.
- 異なるアミノ酸基板 (l-スレオニン,l-ノルヴァリン,l-アミノバター酸) に対して,Fe-(2) H距離とN-Fe-(2) H角を決定した.
主要な成果:
- 各アミノ酸の鉄の中心に対する基板の位置付けのための明確な幾何学的なパラメータを確立しました.
- 異なるFe-(2) H距離 (スレオニンの場合は4.2 Å,ノルヴァリンの場合は3.4 Å) とN-Fe-(2) H角度 (スレオニンの場合は85°,ノルヴァリンの場合は65°) が観察されました.
- これらの幾何学的差異は,観察された反応性傾向 (塩素化対水酸化) と直接相関しています.
結論:
- サブストラットの位置は,SyrB2.2の反応結果の決定的な決定因子です.
- 実験的な相関は,構造データに基づいてFe/2OG酸素酶の活性に対する予測モデルを提供します.
- この研究は,Fe/2OG酵素の触媒メカニズムを理解し,予測するのに役立ち,水酸化抑制や中間物質の形成におけるその役割を含む.
関連する概念動画
02:52Predicting Products: Substitution vs. Elimination
15.2K
When a nucleophile and an alkyl halide react, nucleophilic substitution and β-elimination reactions compete to generate products.
The following factors can influence the mechanisms competing against each other:
The following factors can influence the mechanisms competing against each other:
15.2K
02:27Predicting Products: SN1 vs. SN2
17.9K
Nucleophilic substitution reactions of alkyl halides can proceed via an SN1 or an SN2 mechanism. While in SN2 reactions, the nucleophile attacks the substrate simultaneously as the leaving group departs, in SN1 reactions, the substrate first dissociates to give the carbocation intermediate. Various factors such as the structure of the substrate, the strength of the nucleophile, and the nature of the solvent promote one mechanism over the other.
With increased substitution on the alkyl halide,...
With increased substitution on the alkyl halide,...
17.9K
02:45E2 Reaction: Kinetics and Mechanism
13.7K
SN2 substitutions and E2 eliminations of alkyl halides proceed via a concerted pathway. While the nucleophile attacks the alpha carbon in SN2 reactions, it functions as a strong base and abstracts a beta hydrogen in the E2 mechanism. The rate-limiting transition state in E2 elimination reactions is characterized by partially broken carbon–hydrogen and carbon–halogen bonds and a partially formed pi bond between the alpha and beta carbons. The beta hydrogen and halide are eliminated...
13.7K
02:26SN2 Reaction: Transition State
13.2K
An SN2 reaction of an alkyl halide is a single-step process in which bond formation between the nucleophile and the substrate and bond breaking between the substrate and the halide occurs simultaneously through a transition state without forming an intermediate.
When the nucleophile approaches the electrophilic carbon with its lone pairs, the halide acts as a leaving group and moves away with the electron-pair bonded to the carbon. Dotted partial bonds represent the bonds being formed or broken...
When the nucleophile approaches the electrophilic carbon with its lone pairs, the halide acts as a leaving group and moves away with the electron-pair bonded to the carbon. Dotted partial bonds represent the bonds being formed or broken...
13.2K
02:23SN2 Reaction: Stereochemistry
13.1K
In an SN2 reaction, the nucleophilic attack on the substrate and departure of the leaving group occurs simultaneously through a transition state. As the nucleophile approaches the substrate from the back-side, the configuration of the substrate carbon changes from tetrahedral to trigonal bipyramidal and then back to tetrahedral, leading to an inversion in the configuration of the product.
If the substrate is an achiral molecule at the α-carbon, the inversion of configuration is not...
If the substrate is an achiral molecule at the α-carbon, the inversion of configuration is not...
13.1K
02:17Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule
18.8K
If a set of reactants can yield multiple constitutional isomers, but one of the isomers is obtained as the major product, the reaction is said to be regioselective. In such reactions, bond formation or breaking is favored at one reaction site over others.
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...
18.8K