Video Experimental Relacionado
Updated: Jul 26, 2026
14:11
Quantification of Hydrogen Concentrations in Surface and Interface Layers and Bulk Materials through Depth Profiling with Nuclear Reaction Analysis
Published on: March 29, 2016
Determinación de los acoplamientos escalares homonucleares (1) H en carbohidratos no etiquetados
Catherine Zwahlen1, Sébastien J F Vincent
1Université de Lausanne, Institut de Chimie Organique, CH-1015 Lausanne, Switzerland.
Journal of the American Chemical Society
|June 13, 2002
Resumen
Este estudio introduce un nuevo experimento de RMN para medir parámetros estructurales cruciales en los carbohidratos. Este método supera las limitaciones en el análisis de grandes biomoléculas como los polisacáridos y las glicoproteínas.
Área de la Ciencia:
- Química de los carbohidratos Química de los carbohidratos
- Biología Estructural Biología estructural.
- Espectroscopia de Resonancia Magnética Nuclear (RMN) Espectroscopia de Resonancia Magnética Nuclear (RMN) Espectroscopia de Resonancia Magnética Nuclear (RMN) Espectroscopia de Resonancia Magnética Nuclear (RMN) Espectroscopia de Resonancia Magnética Nuclear (RMN) Espectroscopia de Resonancia Magnética Nuclear (RMN) Espectroscopia de Resonancia Magnética Nuclear (RMN) Espectroscopia de Resonancia Magnética Nuclear (RMN) Espectroscopia de Resonancia Magnética Nuclear (RMN) Espectroscopia de Resonancia Magnética Nuclear (RMN) Espectroscopia de Resonancia Magnética Nuclear (RMN) Espectroscopia de Resonancia Magnética Nuclear (RMN)
Sus antecedentes:
- La aclaración estructural de los carbohidratos es un desafío debido a las dificultades en la cristalización y las limitaciones del análisis actual de RMN.
- Los métodos existentes para determinar los acoplamientos escalares homonucleares de (1) H son insuficientes para las biomoléculas grandes como los polisacáridos y las glicoproteínas.
Objetivo del estudio:
- Presentar un nuevo experimento de RMN para la determinación de acoplamientos escalares endocíclicos (1) H homonucleares ((3) J(HH)) en carbohidratos sin etiquetar.
- Para medir las tasas de relajación dipolo-dipolo de correlación cruzada para los polisacáridos grandes utilizando la técnica de RMN desarrollada.
Principales métodos:
- Desarrollo y aplicación de un nuevo experimento de RMN para la determinación del acoplamiento escalar homonuclear de (1) H.
- Medición de las constantes de acoplamiento endocíclico y las tasas de relajación dipolo-dipolo de correlación cruzada.
Principales resultados:
- El experimento de RMN determinó con éxito los acoplamientos escalares homonucleares endocíclicos (1) H en los carbohidratos.
- Todas las constantes de acoplamiento homonuclear endocíclico se midieron para la lactosa, un modelo de disacárido.
- El método se aplicó a un polisacárido bacteriano de 2 MDa de Streptococcus thermophilus Sfi39, obteniendo información de acoplamiento estructural.
Conclusiones:
- El experimento de RMN presentado avanza significativamente en el análisis estructural de los carbohidratos, particularmente las biomoléculas grandes y sin etiqueta.
- Esta técnica proporciona datos esenciales de acoplamiento escalar, mejorando la resolución estructural de los polisacáridos y las glicoproteínas.
- El estudio demuestra la aplicabilidad del método a productos naturales complejos, incluidos los polisacáridos bacterianos.
Videos de Conceptos Relacionados
02:05Degree of Unsaturation
The degree of unsaturation (U), or index of hydrogen deficiency (IHD), is defined as the difference in the number of pairs of hydrogen atoms between the compound and the acyclic alkane with the same number of carbon atoms. Each double bond or ring costs two hydrogen atoms compared to a saturated analog and results in one degree of unsaturation.
The degree of unsaturation for hydrocarbons is U = (2C + 2 − H) / 2, where C is the number of carbon atoms and H is the number of hydrogen atoms.
For...
The degree of unsaturation for hydrocarbons is U = (2C + 2 − H) / 2, where C is the number of carbon atoms and H is the number of hydrogen atoms.
For...
01:192D NMR: Heteronuclear Single-Quantum Correlation Spectroscopy (HSQC)
Heteronuclear single-quantum correlation spectroscopy (HSQC) is a 2D NMR technique that reveals one-bond correlations between hydrogen and a heteronucleus. The HSQC experiment is similar to the heteronuclear correlation experiment (HETCOR) but is more sensitive. In the HSQC spectrum, the proton chemical shift is plotted on the horizontal F2 axis, while the 13C chemical shift is plotted on the vertical F1 axis. The corresponding proton and 13C spectra are also shown. The HSQC contour plot does...
01:15High-Resolution Mass Spectrometry (HRMS)
The resolution of a mass spectrometer depends on the efficiency of separating ions with different ion masses. The mass of an atom is approximated to the sum of the masses of protons and neutrons inside, considering the masses of protons and neutrons as equal. However, the masses of the proton (1.6726 × 10−24 g) and neutron (1.6749 × 10−24 g) are not truly equal. There is a minor error in the expression of atomic masses relative to the simplest atom of hydrogen. For example, the mass of helium...
01:04¹³C NMR: ¹H–¹³C Decoupling
The probability of having two carbon-13 atoms next to each other is negligible because of the low natural abundance of carbon-13. Consequently, peak splitting due to carbon-carbon spin-spin coupling is not observed in spectra. However, protons up to three sigma bonds away split the carbon signal according to the n+1 rule, resulting in complicated spectra.
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
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...
01:182D NMR: Overview of Heteronuclear Correlation Techniques
Heteronuclear correlation spectroscopy is an analytical technique that investigates the coupling between different types of nuclei, often a proton and an X-nucleus, such as carbon-13 or nitrogen-15. This method is commonly used in nuclear magnetic resonance (NMR) spectroscopy to gain insights into complex chemical compounds' structural and compositional aspects. A typical heteronuclear correlation spectrum displays X-nucleus chemical shifts on one axis and a proton spectrum on the other axis.