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Updated: Jul 8, 2026

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Determination of the Gas-phase Acidities of Oligopeptides
Published on: June 24, 2013
アラニンのガス相構造
Susana Blanco1, Alberto Lesarri, Juan C López
1Contribution from the Grupo de Espectroscopía Molecular (GEM), Departamento de Química Física y Química Inorgánica, Facultad de Ciencias, Universidad de Valladolid, 47005 Valladolid, Spain.
Journal of the American Chemical Society
|September 16, 2004
まとめ
研究者は,中性アラニンを研究するために,レーザー-アブレーション分子ビームフーリエ変換マイクロ波スペクトロスコピーを使用しました. 彼らは2つの安定したアラニンコンフォームの構造を決定し,非平面的骨格とそれぞれの異なる水素結合パターンを明らかにしました.
科学分野:
- 物理化学 物理化学
- スペクトル顕微鏡検査です.
- 分子構造の決定 分子構造の決定
背景:
- アラニンは基本的なアミノ酸で,生化学と薬剤設計に意味があります.
- アラニンの形状のパターンを理解することは,生物学的システムにおけるアラニンの振る舞いを予測する上で極めて重要です.
- 以前の研究では,中性アラニンコンフォーマーの詳細な実験構造データがなかった.
研究 の 目的:
- 最も安定した中性アラニンコンフォームの正確な分子構造を実験的に決定する.
- これらのコンフォマーを安定させる水素結合相互作用を調査する.
- 高解像度スペクトロスコピクデータを用いてコンフォマー構造を割り当て,確認する.
主な方法:
- レーザーアブレーション分子ビームフーリエ変換マイクロ波光譜法 (LA-MB-FTMW) を採用して,高解像度回転スペクトルを取得しました.
- 同位体として標識されたアラニン種 ((15) N, (13) C, D) は,スペクトルの割り当てを助けるために研究されました.
- 核四極結合の超微細な構造が解明され,分析されました.
主要な成果:
- 2つの安定したアラニンコンフォーマーの回転スペクトルが観察され,割り当てられました.
- 両方のコンフォーマーの実験構造は,r(s) とr(0) の方法を使用して決定され,非平面の脊椎を明らかにした.
- コンフォマーIは,二分化水素結合を持つシスCOOH群を示し,コンフォマーIIaは,O-H...N水素結合によって安定したトランスCOOH群を有する.
結論:
- この研究は,2つの中性アラニンコンフォーマーの独立した構造の最初の実験的決定を提供します.
- 解決された核四極結合構造は,コンフォマー割り当てを明確に確認しています.
- アラニンの構造的好みと安定作用の詳細な洞察が得られた.
関連する概念動画
Lewis Structures of Molecular Compounds and Polyatomic Ions
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Acid Strength and Molecular Structure
Binary Acids and Bases
In the absence of any leveling effect, the acid strength of binary compounds of hydrogen with nonmetals (A) increases as the H-A bond strength decreases down a group in the periodic table. For group 17, the order of increasing acidity is HF < HCl < HBr < HI. Likewise, for group 16, the order of increasing acid strength is H2O < H2S < H2Se < H2Te. Across a row in the periodic table, the acid strength of binary hydrogen compounds increases with increasing...
In the absence of any leveling effect, the acid strength of binary compounds of hydrogen with nonmetals (A) increases as the H-A bond strength decreases down a group in the periodic table. For group 17, the order of increasing acidity is HF < HCl < HBr < HI. Likewise, for group 16, the order of increasing acid strength is H2O < H2S < H2Se < H2Te. Across a row in the periodic table, the acid strength of binary hydrogen compounds increases with increasing...
Lewis Structures and Formal Charges
Lewis symbols can be used to indicate the formation of covalent bonds, which are shown in Lewis structures—drawings that describe the bonding in molecules and polyatomic ions. The periodic table can be used to predict the number of valence electrons in an atom and the number of bonds that will be formed to reach an octet. Group 18 elements, such as argon and helium, have filled electron configurations and thus rarely participate in chemical bonding. However, atoms from group 17, such as bromine...
Structures of Carboxylic Acid Derivatives
Structure of Carboxylic Acid Derivatives
Carboxylic acid derivatives contain an acyl group attached to a heteroatom such as chlorine, oxygen, or nitrogen. The carbonyl carbon and oxygen are both sp2-hybridized with an unhybridized p orbital.
The three sp2 orbitals of the carbonyl carbon form three σ bonds, one each with the carbonyl oxygen, the α carbon, and the heteroatom, whereas the other two sp2 orbitals of the carbonyl oxygen are occupied by the lone pairs. Further, the unhybridized p...
Carboxylic acid derivatives contain an acyl group attached to a heteroatom such as chlorine, oxygen, or nitrogen. The carbonyl carbon and oxygen are both sp2-hybridized with an unhybridized p orbital.
The three sp2 orbitals of the carbonyl carbon form three σ bonds, one each with the carbonyl oxygen, the α carbon, and the heteroatom, whereas the other two sp2 orbitals of the carbonyl oxygen are occupied by the lone pairs. Further, the unhybridized p...
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...
Structures of Aldehydes and Ketones
Vanillin—a flavoring agent in vanilla, cinnamaldehyde—a molecule responsible for the distinct smell of cinnamon, and acetone—a strong-smelling ingredient in nail polish removers, all belong to a class of carbonyl compounds called aldehydes and ketones (Figure 1). Although both aldehydes and ketones contain the characteristic carbonyl (C=O) bond, their chemical structures vary with respect to the groups directly attached to the carbonyl carbon.
In aldehydes (Figures 1a and 1b), the carbonyl...
In aldehydes (Figures 1a and 1b), the carbonyl...

