Video Experimental Relacionado
Updated: Jun 28, 2026
08:22
Measurement of Ultrafast Vibrational Coherences in Polyatomic Radical Cations with Strong-Field Adiabatic Ionization
Published on: August 6, 2018
Estructura de los fragmentos de disociación de captura de electrones de péptidos etiquetados con carga probados por
Gilles Frison1, Guillaume van der Rest, Frantisek Turecek
1Laboratoire des Mécanismes Réactionnels, Department of Chemistry, Ecole Polytechnique and CNRS, 91128 Palaiseau, France.
Journal of the American Chemical Society
|October 22, 2008
Resumen
La disociación por captura de electrones (ECD, por sus siglas en inglés) forma iones peptídicos tipo c con una estructura amida, no uno enol-imino. Este hallazgo aclara el mecanismo de ECD utilizando espectroscopia infrarroja.
Área de la Ciencia:
- Espectrometría de masas por espectrometría de masas.
- Física Química Física Química es la física de la química.
- Biología Estructural Biología estructural.
Sus antecedentes:
- La caracterización estructural de los iones de péptido tipo c generados a través de la disociación de captura de electrones (ECD) sigue siendo un tema de debate.
- Las estructuras propuestas incluyen formas enol-iminas y amidas, que son isómeros e indistinguibles solo por espectrometría de masas.
Objetivo del estudio:
- Determinar espectroscópicamente la estructura de los iones tipo c producidos por ECD.
- Para dilucidar el mecanismo de formación de iones de tipo c en ECD.
Principales métodos:
- Acoplamiento de un láser sintonizable de electrones libres con un espectrómetro de masas de resonancia de ciclotrón de iones de la transformada de Fourier (FT-ICR).
- Espectroscopia infrarroja (IR) para diferenciar entre las estructuras iónicas isoméricas.
Principales resultados:
- La evidencia espectroscópica confirma que los iones de tipo c poseen una estructura amida (-C(O) -NH2).
- Se observó una firma IR característica del tramo C = O a 1731 cm.
Conclusiones:
- El estudio establece definitivamente la estructura amida de los iones tipo c formados por ECD.
- Esta determinación estructural proporciona información crítica sobre el mecanismo fundamental de la disociación de la captura de electrones.
Videos de Conceptos Relacionados
01:21Tandem Mass Spectrometry
Tandem mass spectrometry is a technique that uses multiple mass analyzers in series to obtain a higher selectivity and reduce chemical noise during analyte detection. Instruments with multiple analyzers separated by an interaction cell enable secondary fragmentation and selected study of the fragment ions.Secondary fragmentations occur in the interaction cell and can be induced by various factors. Fragmentation induced by collision with inert gases, such as N2, Ar, He, etc., is called...
01:20Mass Spectrometry: Molecular Fragmentation Overview
The ionization of a molecule into a molecular ion inside the mass spectrometer causes instability in the molecule's structure due to the loss of an electron. This eventually leads to the fragmentation or breaking of some bonds in the molecule. The fragmentation occurs predominantly at specific bonds to yield relatively stable fragments.
One type of fragmentation pattern is the cleavage of a single bond in the molecular ion. The cleavage leads to a radical and a cation. The cleavage can occur at...
One type of fragmentation pattern is the cleavage of a single bond in the molecular ion. The cleavage leads to a radical and a cation. The cleavage can occur at...
01:01Mass Spectrometry: Carboxylic Acid, Ester, and Amide Fragmentation
The fragmentation patterns observed for compounds such as carboxylic acids, esters, and amides in the mass spectra include ⍺-cleavage and McLafferty rearrangement. Fragmentation by ⍺-cleavage preferentially occurs at the carbon-carbon bond at the ⍺-position next to the carboxylic group to generate a neutral radical and a cation. Long chain compounds with hydrogen at their γ-carbon undergo McLafferty rearrangement to give a radical cation and a neutral alkene.
For example, the fragmentation of...
For example, the fragmentation of...
01:24Mass Spectrum: Interpretation
An unknown compound can be established by identifying the molecular ion peak in the mass spectrum. The molecular ion peak is often weak or absent due to the predominance of fragmentation in high-energy electron beams. In such cases, a soft-energy electron beam can be used to scan the spectrum to enhance the intensity of the molecular ion peak. Additionally, chemical ionization, field ionization, and desorption ionization spectra are used to obtain a relatively intense molecular ion peak.To...
01:33Peptide Identification Using Tandem Mass Spectrometry
Tandem mass spectrometry, also known as MS/MS or MS2, is an analytical technique that employs two mass analyzers. Essentially it is a series of mass spectrometers that helps isolate a particular biomolecule and then helps study its chemical properties.
This technique helps gather information regarding the protein from which the peptide was obtained and to study the peptides’ amino acid sequence. Identifying peptides from a complex mixture is an important component of the growing field of...
This technique helps gather information regarding the protein from which the peptide was obtained and to study the peptides’ amino acid sequence. Identifying peptides from a complex mixture is an important component of the growing field of...
01:20¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
When proton-coupled carbon-13 spectra are simplified by a broadband proton decoupling technique, structural information about the coupled protons is lost. Distortionless enhancement by polarization transfer (DEPT) is a technique that provides information on the number of hydrogens attached to each carbon in a molecule. While the DEPT experiment utilizes complex pulse sequences, the pulse delay and flip angle are specifically manipulated. The resulting signals have different phases depending on...