Video Experimental Relacionado
Updated: Jul 15, 2026
14:55
Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
Probar el conjunto de estados de transición de una reacción de plegamiento de proteínas mediante la dispersión de
Dmitry M Korzhnev1, Irina Bezsonova, Ferenc Evanics
1Department of Medical Genetics, University of Toronto, Toronto, Ontario, Canada, M5S 1A8.
Journal of the American Chemical Society
|April 13, 2006
Resumen
Este estudio revela que el conjunto de estados de transición (TSE) en el plegamiento de proteínas está colapsado, suelto e hidratado. La liberación de agua se produce después del paso limitador de velocidad, lo que influye en las barreras plegables.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- La biofísica es la biofísica.
- Biología Estructural Biología estructural.
Sus antecedentes:
- Apocitocromo b562 es una proteína modelo para el estudio de los mecanismos de plegamiento.
- Comprender las vías de plegamiento de proteínas es crucial para comprender la función biológica y la enfermedad.
Objetivo del estudio:
- Para investigar los cambios volumétricos y de compresibilidad durante el plegado de un apocitocromo b562 mutante rediseñado (F61A/A90G).
- Para caracterizar el conjunto de estados de transición (TSE) del plegamiento de proteínas utilizando métodos de perturbación de presión.
Principales métodos:
- Dependencia de presión utilizada de los perfiles de velocidad de dispersión de relajación de RMN de 15N.
- Se estudió el equilibrio de plegado/despliegue a varias presiones (1-270 bar) sin desnaturalizantes.
- Parámetros volumétricos analizados y compresibilidad isotérmica.
Principales resultados:
- Se midió un cambio de volumen para el despliegue de -81 ml/mol.
- Se determinó la compresibilidad de la EET en relación con el estado desplegado (0,15 ml mol(-1) bar(-1)).
- Se observó una dependencia de presión no lineal de los cambios de energía libre, lo que indica un TSE hidratado y colapsado.
Conclusiones:
- El conjunto del estado de transición se caracteriza como colapsado, sueltamente empacado e hidratado.
- La liberación de agua ocurre principalmente después de la etapa de limitación de velocidad en el proceso de plegado.
- Los hallazgos apoyan una barrera entrópica para el plegamiento a 45°C para esta proteína mutante.
Videos de Conceptos Relacionados
01:13¹H NMR: Complex Splitting
A proton M that is coupled to a proton X results in doublet signals for M. However, NMR-active nuclei can be simultaneously coupled to more than one nonequivalent nucleus. When M is coupled to a second proton A, such as in styrene oxide, each peak in the doublet is split into another doublet.
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied first.
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied first.
01:02¹H NMR: Interpreting Distorted and Overlapping Signals
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 slanted or...
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 slanted or...
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...
01:15Insensitive Nuclei Enhanced by Polarization Transfer (INEPT)
Insensitive Nuclei Enhanced by Polarization Transfer (INEPT) is an advanced Nuclear Magnetic Resonance (NMR) technique specifically designed to detect and enhance the signals of low-abundance nuclei, such as carbon-13 and nitrogen-15, in small molecules. The fundamental principle behind INEPT is the transfer of polarization from a more abundant and highly polarizable nucleus, typically hydrogen-1, to the low-abundance nucleus of interest. This process effectively boosts the NMR signal of the...
01:12Double Resonance Techniques: Overview
Double resonance techniques in Nuclear Magnetic Resonance (NMR) spectroscopy involve the simultaneous application of two different frequencies or radiofrequency pulses to manipulate and observe two distinct nuclear spins. One important application of double resonance is spin decoupling, which selectively suppresses coupling with one type of nucleus while observing the NMR signal from another nucleus, simplifying the spectrum and enhancing resolution.
Spin decoupling is usually achieved by...
Spin decoupling is usually achieved by...
01:162D NMR: Overview of Homonuclear Correlation Techniques
Homonuclear correlation spectroscopy (COSY) is a powerful technique used in Nuclear Magnetic Resonance (NMR) spectroscopy to study the correlations between nuclei of the same type within a molecule. It provides information about scalar couplings between adjacent nuclei, which helps determine connectivity and structural information. There are several COSY variants, each with its unique strengths and experimental parameters.
COSY90 is the standard two-dimensional (2D) COSY experiment that...
COSY90 is the standard two-dimensional (2D) COSY experiment that...