关氨酸基对的微水化
Ali Abo-Riziq1, Bridgit Crews, Louis Grace
1Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, USA.
Journal of the American Chemical Society
|February 24, 2005
概括
光谱学揭示了水分子如何与瓜基对相互作用. 一个单一的水分子稳定了特定的瓜二元结构,而第二个水分子没有额外的结构效应.
科学领域:
- 物理化学 物理化学
- 分子光谱学 分子光谱学
- 生物物理学的生物物理.
背景情况:
- 关氨酸基对是DNA和RNA结构的基础.
- 了解水对基对稳定性的影响,对于分子生物学来说至关重要.
- 之前的研究已经确定了瓜二元体的两个潜在结构.
研究的目的:
- 为了研究水分子对瓜基对集群的结构效应.
- 用先进的光谱技术来描述瓜二元和水分子之间的特定相互作用.
主要方法:
- 共振双光子电离 (R2PI) 谱学用于记录质量选择的GG(H2O) 和GG(H2O) 2星团的振动光谱.
- 红外-紫外 (IR-UV) 双共振光谱法,以获得地面状态的红外光谱.
主要成果:
- 一个单一的水分子被发现稳定了两种先前识别的瓜二分体结构之一.
- 添加第二个水分子并没有诱导瓜二元集群中的任何进一步的结构修改.
结论:
- 水分子在稳定关基对的特定形状方面发挥着重要作用.
- 水对瓜二次体的稳定作用似乎只需添加一个水分子,就会达到和.
相关概念视频
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The reaction between a Brønsted-Lowry acid and water is called acid ionization. For example, when hydrogen fluoride dissolves in water and ionizes, protons are transferred from hydrogen fluoride molecules to water molecules, yielding hydronium ions and fluoride ions:
02:45Acid-Catalyzed Hydration of Alkenes
Alkenes react with water in the presence of an acid to form an alcohol. In the absence of acid, hydration of alkenes does not occur at a significant rate, and the acid is not consumed in the reaction. Therefore, alkene hydration is an acid-catalyzed reaction.
02:34Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
The rate of acid-catalyzed hydration of alkenes depends on the alkene's structure, as the presence of alkyl substituents at the double bond can significantly influence the rate.
01:20Aldehydes and Ketones with Water: Hydrate Formation
An oxygen-based nucleophile, like water, can undergo addition reactions with aldehydes and ketones. The reaction leads to the formation of hydrates, also referred to as 1,1-diols or geminal diols.
The formation of hydrates is a reversible reaction. Hydrate formation is influenced by steric and electronic factors accompanying the alkyl substituents on the carbonyl group: The rate of hydrate formation increases with a decrease in the number of alkyl groups attached to the carbonyl carbon. Hence,...
The formation of hydrates is a reversible reaction. Hydrate formation is influenced by steric and electronic factors accompanying the alkyl substituents on the carbonyl group: The rate of hydrate formation increases with a decrease in the number of alkyl groups attached to the carbonyl carbon. Hence,...
01:01Acid Halides to Carboxylic Acids: Hydrolysis
Hydrolysis of acid halides is a nucleophilic acyl substitution reaction in which acid halides react with water to give carboxylic acids. The reaction occurs readily and does not require acid or a base catalyst.
As shown below, the mechanism involves a nucleophilic attack by water at the carbonyl carbon to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen π bond along with the departure of a halide ion. A final proton transfer step yields carboxylic acid...
As shown below, the mechanism involves a nucleophilic attack by water at the carbonyl carbon to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen π bond along with the departure of a halide ion. A final proton transfer step yields carboxylic acid...
01:25Basicity of Heterocyclic Aromatic Amines
Heterocyclic amines, where the N atom is a part of an alicyclic system, are similar in basicity to alkylamines. Interestingly, the heterocyclic amine having a nitrogen atom as part of an aromatic ring has much less basicity than its corresponding alicyclic counterpart. For this reason, as presented in Figure 1, piperidine (pKb = 2.8) is significantly more basic than pyridine (pKb = 8.8).