合成 [2Fe-2S] および [4Fe-4S] クラスターの酸化窒素およびニトロソチオールとの反応
Todd C Harrop1, Zachary J Tonzetich, Erwin Reisner
1Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Journal of the American Chemical Society
|October 23, 2008
まとめ
酸化窒素 (NO) は,鉄硫黄のクラスターと反応し,ダイナトロシル鉄複合体 (DNIC) を形成する. この研究は,NO NOを調査しています.
科学分野:
- バイオ・オーガニック化学 バイオ・オーガニック化学
- 協調化化学について
- バイオケミストリー バイオケミストリー
背景:
- 酸化窒素 (NO) は鉄硫黄タンパク質と相互作用し,クラスター分解とディニトロシル鉄複合体 (DNIC) の形成につながります.
- DNICの形成は,酵素の活動を変化させ,生物学的システムにおける調節経路を活性化させることができます.
研究 の 目的:
- 酸化窒素と合成 [2Fe-2S]および [4Fe-4S]クラスターの間の反応の基本的な化学を調査する.
- これらの反応の経路と産物を解明し,生物学的過程の洞察を提供すること.
主な方法:
- 合成 [2Fe-2S] と [4Fe-4S] のクラスターとガス状酸化窒素 (NO) の反応.
- 構造の決定のためのX線結晶学を含む反応産物の特性.
- トリチル-S-ニトロソチオール (Ph3CSNO) を代替の酸化窒素源として利用した.
主要な成果:
- [2Fe-2S]クラスターがNO過剰で反応すると,DNIC ([Fe(NO) 2 ((SR) 2) ((-)) と元素硫黄が生成されます.
- [4Fe-4S]クラスターはNOと反応して,余分なチオラートがない状態で,ルッシン黒塩 ([Fe4S3(NO) [7](-)) を形成した.
- 十分なチオラートの存在は,4Fe-4S]クラスターからのDNIC形成を安定させ,Ph3CSNOとの反応を反映した.
結論:
- この研究は,生物学的文脈における酸化窒素と鉄硫黄のクラスターの妥当な反応経路を示しています.
- ディニトロシル鉄複合体の安定化におけるチオラートと鉄の比率の重要な役割を強調する.
関連する概念動画
Preparation and Reactions of Thiols
Thiols are prepared using the hydrosulfide anion as a nucleophile in a nucleophilic substitution reaction with alkyl halides. For instance, bromobutane reacts with sodium hydrosulfide to give butanethiol.
Preparation and Reactions of Sulfides
Sulfides are the sulfur analog of ethers, just as thiols are the sulfur analog of alcohol. Like ethers, sulfides also consist of two hydrocarbon groups bonded to the central sulfur atom. Depending upon the type of groups present, sulfides can be symmetrical or asymmetrical. Symmetrical sulfides can be prepared via an SN2 reaction between 2 equivalents of an alkyl halide and one equivalent of sodium sulfide.
2° Amines to N-Nitrosamines: Reaction with NaNO2
Secondary amines react with nitrous acid to form N-nitrosamines, as depicted in Figure 1. Nitrous acid, a weak and unstable acid, is formed in situ from an aqueous solution of sodium nitrite and strong acids, such as hydrochloric acid or sulfuric acid, in cold conditions. In the presence of an acid, the nitrous acid gets protonated. The subsequent loss of water results in the formation of the electrophile known as nitrosonium ion.
Nitrosation of Enols
The nitrosation reaction is one of the methods of preparing 1,2-diketones. The enol tautomer of the starting ketone reacts with sodium nitrite in hydrochloric acid, generating the 1,2-diketone after hydrolysis.
Rate-Determining Steps
Relating Reaction Mechanisms
In a multistep reaction mechanism, one of the elementary steps progresses significantly slower than the others. This slowest step is called the rate-limiting step (or rate-determining step). A reaction cannot proceed faster than its slowest step, and hence, the rate-determining step limits the overall reaction rate.
The concept of rate-determining step can be understood from the analogy of a 4-lane freeway with a short-stretch of traffic-bottleneck caused due to...
In a multistep reaction mechanism, one of the elementary steps progresses significantly slower than the others. This slowest step is called the rate-limiting step (or rate-determining step). A reaction cannot proceed faster than its slowest step, and hence, the rate-determining step limits the overall reaction rate.
The concept of rate-determining step can be understood from the analogy of a 4-lane freeway with a short-stretch of traffic-bottleneck caused due to...
Preparation of Nitriles
One of the common methods to prepare nitriles is the dehydration of amides. This method requires strong dehydrating agents like phosphorous pentoxide or boiling acetic anhydride for converting amides to nitriles. Another reagent namely, thionyl chloride also accomplishes the dehydration of amides, where amide acts as a nucleophile. The first step of the mechanism involves the nucleophilic attack by the amide on the thionyl chloride to form an intermediate. In the next step, the electron pairs...


