Video Experimental Relacionado
Updated: May 7, 2026
04:37
High-Pressure NMR Experiments for Detecting Protein Low-Lying Conformational States
Published on: June 29, 2021
2.2K
Las constantes dieléctricas de las proteínas se determinan a partir de las perturbaciones de desplazamiento químico
Predrag Kukic1, Damien Farrell, Lawrence P McIntosh
1School of Biomolecular and Biomedical Science, Centre for Synthesis and Chemical Biology, UCD Conway Institute, University College Dublin , Belfield, Dublin 4, Ireland.
Journal of the American Chemical Society
|October 16, 2013
Resumen
Este estudio determinó las constantes dieléctricas óptimas para las proteínas mediante la medición de campos eléctricos utilizando perturbaciones de desplazamiento químico de RMN. Los hallazgos sugieren un nuevo valor intrínseco para las constantes dieléctricas de las proteínas, cruciales para cálculos electrostáticos precisos.
Área de la Ciencia:
- La biofísica es la biofísica.
- Biología Estructural Biología estructural.
- Química computacional es la química computacional.
Sus antecedentes:
- Los cálculos electrostáticos precisos son vitales para comprender las relaciones estructura-función de las proteínas.
- Existe un debate de larga data con respecto a las constantes dieléctricas apropiadas (ε ((eff) y ε ((p)) para los modelos de proteínas.
- Los valores actuales de la constante dieléctrica son empíricos e indirectamente medidos, lo que limita su aplicabilidad general.
Objetivo del estudio:
- Para determinar las constantes dieléctricas óptimas (ε(eff) y ε(p)) para las proteínas.
- Para medir directamente los campos eléctricos de las proteínas utilizando perturbaciones de desplazamiento químico de RMN (CSP).
- Establecer constantes dieléctricas más precisas y transferibles para el modelado electrostático.
Principales métodos:
- Se midieron CSPs en 14 proteínas diversas para caracterizar los campos eléctricos.
- Aplicó la ley de Coulomb para correlacionar las CSP con las constantes dieléctricas.
- Utilizó cálculos de diferencia finita Poisson-Boltzmann para el análisis de interfaz.
Principales resultados:
- El ε (((eff) óptimo osciló entre 3 y 13, con una media de 6.5, cuando se utiliza la ley de Coulomb.
- Se encontró que el εp óptimo era 3 (rango 2-5) al considerar la interfaz agua-proteína a través de los cálculos de Poisson-Boltzmann.
- El ε ((p) determinado de 3 se alinea con los valores de las mediciones de polvo de proteína, a diferencia de los valores más altos utilizados para los cálculos termodinámicos.
Conclusiones:
- La constante dieléctrica derivada de 3 para las proteínas plegadas es probablemente intrínseca y transferible, reflejando el campo eléctrico con precisión.
- Este valor difiere significativamente de los utilizados en los modelos basados en parámetros termodinámicos.
- Los hallazgos proporcionan una base más sólida para los cálculos electrostáticos basados en la estructura de las proteínas.
Más Videos Relacionados
Videos de Conceptos Relacionados
01:15NMR Spectroscopy: Chemical Shift Overview
3.6K
The position of the absorption signal of a sample is reported relative to the position of the signal of tetramethylsilane (TMS), which is added as an internal reference while recording spectra. The difference between the absorption frequencies of the sample and TMS (in Hz) is divided by the spectrometer operating frequency (in MHz) to obtain a dimensionless quantity called the chemical shift. It is reported on the δ (delta) scale and expressed in parts per million.
For instance, the proton...
For instance, the proton...
3.6K
01:20¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
1.3K
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...
1.3K
01:26Susceptibility, Permittivity and Dielectric Constant
3.7K
When placed in an external electric field, a dielectric material gets polarized. The charge density in the dielectric material is given by the sum of the bound and free charge densities, while the total charge density can also be written in terms of the total electric field. The bound charge density can be measured in terms of polarization, leading to the relationship between electric displacement and polarization.
3.7K
01:07Proton (¹H) NMR: Chemical Shift
3.8K
Organic molecules primarily contain carbon and hydrogen atoms. While all the hydrogen isotopes are NMR-active, protium or hydrogen-1 is the most abundant. It has a significant energy separation between its nuclear spin states due to its large gyromagnetic ratio. As per Boltzmann's distribution, an increase in the energy separation implies a greater excess population of nuclei available for excitation, resulting in a strong NMR absorption signal.
Absorption signals of all the protium nuclei...
Absorption signals of all the protium nuclei...
3.8K
01:02¹H NMR: Interpreting Distorted and Overlapping Signals
1.3K
Spin systems where the difference in chemical shifts of the coupled nuclei is greater than ten times J are called first-order spin systems. These nuclei are weakly coupled, and their chemical shifts and coupling constant can generally be estimated from the well-separated signals in the spectrum.
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
1.3K
01:27Inductive Effects on Chemical Shift: Overview
2.3K
The protons in unsubstituted alkanes are strongly shielded with chemical shifts below 1.8 ppm. Methine, methylene, and methyl protons appear at approximately 1.7, 1.2 and 0.7 ppm, while the proton signal from methane appears at 0.23 ppm. An electronegative substituent, such as chlorine, withdraws the electron density from the protons, increasing their chemical shift. Progressive substitution of the hydrogens in methane by chlorine shifts the proton signals increasingly downfield, to 3.05 ppm in...
2.3K