在将甲醇添加到水中后,CI-2符合者的变化:基于IMS-MS的热力学分析
Hua Pan1, Shannon A Raab1, Tarick J El-Baba1
1Department of Chemistry, Indiana University, 800 Kirkwood Avenue, Bloomington, Indiana 47401, United States.
The journal of physical chemistry. A
|November 7, 2023
概括
将甲醇添加到水中会改变基摩素抑制剂2 (CI-2) 蛋白质折叠的结构格局. 这项研究揭示了溶剂组成如何影响蛋白质稳定性,以及通过离子移动性光谱/质谱 (IMS/MS) 观察到的众多原生和变质状态的分布.
科学领域:
- 蛋白质折叠热力学和生物物理学
- 溶液状态蛋白质结构分析
- 溶剂对生物分子平衡的影响
背景情况:
- 基托里普辛抑制剂2 (CI-2) 是一种模型蛋白质,表现出两种状态折叠过渡.
- 之前的离子移动性光谱/质谱 (IMS/MS) 研究显示,在水中CI-2热变质过程中,约有41种不同的形状.
- 水的介电常数和蛋白质结构的温度依赖的变化影响了这些状态.
研究的目的:
- 调查甲醇-水混合物对CI-2符合分布和稳定性的影响.
- 为了比较CI-2在水中的热力学参数 (ΔG, ΔH, ΔS, ΔCp) 与60:40水:甲醇 (MeOH) 溶剂系统.
- 了解溶解和温度变化如何影响多态蛋白平衡.
主要方法:
- 混合离子移动性光谱仪 (IMS) /质谱仪 (MS) 与可变温度电喷射电离源相结合.
- 在纯水和60:40水:甲醇混合物中进行CI-2的热变性试验.
- 吉布斯-赫尔姆霍尔茨分析用于从温度依赖的结构数据中推导热力学参数.
主要成果:
- 在60:40的水:MeOH混合物中,在水中观察到的同一组CI-2对应物存在,但它们的相对丰度发生了显著变化.
- 添加甲醇降低了溶剂混合物的介电常数,特别是在更高的温度下.
- 热力学分析显示,水和水:MeOH系统之间的自由能量,,和热容量存在差异.
结论:
- 虽然溶剂介电常数随温度变化而影响蛋白质调整器分布,但其他溶剂特性也起着作用.
- 溶解的变化显著影响了管理蛋白质折叠的多态平衡.
- 这项研究提供了一种罕见的,详细比较不同溶剂环境中的蛋白质构造组合.
相关概念视频
Chemical Ionization (CI) Mass Spectrometry
761
The molecular ion peak of a molecule in the mass spectrum provides vital information for molecular identification. However, conventional electron impact ionization can lead to the rapid dissociation of some molecular ions before they reach the detector. A milder ionization method is required to increase the lifetime of such ionized analyte molecules. Chemical ionization (CI) is a gas-phase protonation reaction useful for mass-analyzing analyte molecules that are easily protonated to yield the...
761
Preparation of Alcohols via Addition Reactions
6.3K
Overview
The acid-catalyzed addition of water to the double bond of alkenes is a large-scale industrial method used to synthesize low-molecular-weight alcohols. An acidic atmosphere is required to allow the hydrogen in the water molecule to act as an electrophile and attack the double bond in an alkene. The addition of a proton to the double bond creates a carbocation intermediate. The proton preferentially bonds to the less substituted end of the double bond to create a more stable carbocation...
The acid-catalyzed addition of water to the double bond of alkenes is a large-scale industrial method used to synthesize low-molecular-weight alcohols. An acidic atmosphere is required to allow the hydrogen in the water molecule to act as an electrophile and attack the double bond in an alkene. The addition of a proton to the double bond creates a carbocation intermediate. The proton preferentially bonds to the less substituted end of the double bond to create a more stable carbocation...
6.3K
Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
8.4K
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.
8.4K
¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR
1.1K
The axial and equatorial protons in cyclohexane can be distinguished by performing a variable-temperature NMR experiment. In this process, except for one proton, the remaining eleven protons are replaced by deuterium. The deuterium substitution avoids the possible peak splitting caused by the spin-spin coupling between the adjacent protons. The remaining proton flips between the axial and equatorial positions.
1.1K
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
855
At room temperature, the chair conformer of cyclohexane undergoes rapid ring flipping between two equivalent chair conformers at a rate of approximately 105 times per second. These two chair conformers are in equilibrium. The rapid ring flipping results in the interconversion of the axial proton to an equatorial proton and an equatorial to the axial proton. Such interconversions are too rapid and cannot be detected on the NMR timescale. Hence, the NMR spectrometer cannot distinguish between the...
855
Conformations of Ethane and Propane
14.0K
In an organic molecule, free rotation about the carbon-carbon single bond results in energetically different conformers of the molecule. Due to this rotation, called the internal rotation, ethane has two major conformations — staggered and eclipsed.
Staggered conformation is a low energy and more stable conformation with the C-H bonds on the front carbon placed at 60°dihedral angles relative to the C-H bonds on the back carbon, leading to a reduced torsional strain. In staggered...
Staggered conformation is a low energy and more stable conformation with the C-H bonds on the front carbon placed at 60°dihedral angles relative to the C-H bonds on the back carbon, leading to a reduced torsional strain. In staggered...
14.0K


