Ab Initio 氨基酸及其在氨基中的氨基基基类型的分子动力学模拟
Henrik Niemöller1, Johannes Ingenmey1, Oldamur Hollóczki2
1Mulliken Center for Theoretical Chemistry, Clausius-Institute for Physical and Theoretical Chemistry, University of Bonn, Beringstraße 4-6, Bonn D-53115, Germany.
The journal of physical chemistry. B
|March 20, 2025
概括
在以氨基为基础的生物化学中,α-氨基胺基因保持中立,与α-氨基酸不同,α-氨基酸变为阳离子. 这种差异影响了它们的结构行为和溶解相互作用,表明氨基酸可能是替代生物化学的关键.
科学领域:
- 天体生物学和生物化学
- 计算化学计算化学
- 化学物理 化学物理
背景情况:
- 地球的生物化学依赖α-氨基酸作为基本的分子构建块.
- 假设的以氨为基础的生命形式可能利用α-氨基胺素作为类似结构.
- 了解非水性溶剂中的溶解物-溶剂相互作用对于探索替代生物化学是至关重要的.
研究的目的:
- 研究氨酸中的α-氨基胺基的基本特性,将其与α-氨基酸进行比较.
- 在氨溶剂中分析这些分子的结构和电子状态.
- 探索氨中质子转移反应和溶解动态的潜力.
主要方法:
- 使用*ab initio*分子动力学模拟来建模分子行为.
- 分析时间解析的分子二极点时刻,以了解形状和状态.
- 追踪质子转移事件,并在溶解过程中量化电荷转移.
主要成果:
- 氨中的α-氨基酸主要采用阴离子状态,而离子形式也可获得.
- 在氨酸中溶解时,α-氨基胺始终保持中性状态.
- 在zwitterionic alanine的deprotonation时观察到Grotthuss扩散,这表明质子的移动性.
- 对α-氨基酸而言,溶解相互作用显著强于对α-氨基酸而不是对α-氨基胺,对后者而言,电荷交换最小.
- 在结构上,阳离子α-氨基酸与中性α-氨基酸氨基酸具有很强的相似性.
结论:
- 与氨中的α-氨基酸相比,α-氨基氨基酸表现出明显的溶解行为,保持中性.
- 溶解时的电荷转移表明α-氨基氨基胺和氨之间相互作用较弱.
- 阳离子α-氨基酸和中性α-氨基胺胺之间的结构相似性表明在不同的生化系统中存在潜在的功能类比.
相关概念视频
Acid Halides to Amides: Aminolysis
Aminolysis is a nucleophilic acyl substitution reaction, where ammonia or amines act as nucleophiles to give the substitution product. Acid halides react with ammonia, primary amines, and secondary amines to yield primary, secondary, and tertiary amides, respectively.
In the first step of the aminolysis mechanism, the amine attacks the carbonyl carbon of the acyl chloride to form a tetrahedral intermediate. In the second step, the carbonyl group is re-formed with the elimination of a chloride...
In the first step of the aminolysis mechanism, the amine attacks the carbonyl carbon of the acyl chloride to form a tetrahedral intermediate. In the second step, the carbonyl group is re-formed with the elimination of a chloride...
Structure of Amines
The hybridized nitrogen atom in amines possesses a lone pair of electrons and is bound to three substituents with a bond angle of around 108°, which is less than the tetrahedral angle of 109.5°. However, the C–N–H bond angle is slightly larger at 112°, with a carbon–nitrogen bond length of 147 pm. This carbon–nitrogen bond length of of amines is longer than the carbon–oxygen bond of alcohols (143 pm) but shorter than alkanes’ carbon–carbon bond (154 pm). These aspects are illustrated in Figure...
Preparation of Amines: Alkylation of Ammonia and Amines
Alkylation is one of the methods used to prepare amines. Direct alkylation of ammonia or a primary amine with an alkyl halide gives polyalkylated amines along with a quaternary ammonium salt through successive SN2 reactions. This process of making the quaternary salt through the direct alkylation method is called exhaustive alkylation.
Each alkylation step makes the nitrogen center more nucleophilic, which triggers successive alkylations until a quaternary ammonium salt is formed. Considering...
Each alkylation step makes the nitrogen center more nucleophilic, which triggers successive alkylations until a quaternary ammonium salt is formed. Considering...
Amines: Introduction
Amines are organic derivatives of ammonia. They are formed by replacing one or more ammonia protons with alkyl or aryl groups. Depending upon the number of organyl groups bonded to nitrogen, amines are classified as primary, secondary, or tertiary. Primary amines have one organyl group attached to the nitrogen atom, while secondary and tertiary amines have two and three organyl groups attached to the nitrogen atom, respectively.
Preparation of 1° Amines: Gabriel Synthesis
Direct alkylation is not a suitable method for synthesizing amines because it produces polyalkylated products. Gabriel synthesis is the most preferred method to exclusively make primary amines. The method uses phthalimide, which contains a protected form of nitrogen that participates in alkylation only once to predominantly give primary amines.
Strong bases like NaOH or KOH deprotonate the phthalimide to form the corresponding anion, which acts as a nucleophile. Further, the anion attacks an...
Strong bases like NaOH or KOH deprotonate the phthalimide to form the corresponding anion, which acts as a nucleophile. Further, the anion attacks an...
NMR Spectroscopy Of Amines
In proton NMR spectroscopy, primary amines and secondary amines showcase their N–H protons as a broad signal in the chemical shift range between δ 0.5 and 5 ppm. The exact position in this range depends on several factors, including sample concentration, hydrogen bonding, and the type of solvent used. Since amine protons undergo fast proton exchange in solution, the protons are labile and therefore do not participate in any splitting with adjacent protons. Thus, the observed peak is broad and...


