Video Experimental Relacionado
Updated: Jun 9, 2026
10:23
Time-Resolved Fluorescence Anisotropy from Single Molecules for Characterizing Local Flexibility in Biomolecules
Published on: April 25, 2025
El espacio conformal de las macromoléculas biológicas flexibles a partir del promedio de los datos
Ivano Bertini1, Andrea Giachetti, Claudio Luchinat
1CERM, University of Florence, Via L. Sacconi 6, 50019 Sesto Fiorentino, Italy. ivanobertini@cerm.unifi.it
Journal of the American Chemical Society
|September 9, 2010
Resumen
Los investigadores desarrollaron un nuevo método para mapear la flexibilidad de las proteínas utilizando datos de ocurrencia máxima (MO). Este análisis revela que las conformaciones proteicas extendidas son más abundantes en solución, a diferencia de las formas compactas.
Área de la Ciencia:
- Biología estructural Biología estructural.
- La biofísica es la biofísica.
- Biología computacional Biología computacional.
Sus antecedentes:
- Las proteínas flexibles exhiben conjuntos conformacionales dinámicos en solución.
- Comprender la dinámica conformacional de las proteínas es crucial para elucidar la función biológica.
Objetivo del estudio:
- Introducir el concepto de ocurrencia máxima (MO) para cuantificar las preferencias conformacionales de las proteínas.
- Desarrollar y validar un método riguroso para construir mapas de MO a partir de datos experimentales.
- Investigar el paisaje conformacional de la calmodulina (CaM) en solución.
Principales métodos:
- Utilizó la dispersión de rayos X de ángulo pequeño (SAXS) para obtener información estructural de baja resolución.
- Espectroscopia de Resonancia Magnética Nuclear (RMN) empleada, incluidos los desplazamientos de pseudocontacto y los acoplamientos dipolares residuales de derivados de lantánidos.
- Desarrolló métodos computacionales para el muestreo de espacio conformacional extenso y la construcción de mapas MO.
Principales resultados:
- Valores de MO determinados para diferentes conformaciones de calmodulina, con formas cristalinas "cerradas" y "completamente extendidas" que muestran bajos MO (5% y 15%).
- Se identificaron conformaciones extendidas con OM de hasta el 35%, lo que indica su prevalencia en solución.
- Demostró que las conformaciones compactas generalmente exhiben MOs más bajos en comparación con las extendidas.
Conclusiones:
- El método desarrollado proporciona una medida cuantitativa de la abundancia conformacional de proteínas en solución.
- Las conformaciones extendidas están significativamente más pobladas en solución de lo que sugerían previamente las estructuras estáticas.
- El método es de amplia aplicación, ya que requiere datos estándar SAXS y datos específicos de RMN de proteínas etiquetadas con lantánidos.
Videos de Conceptos Relacionados
00:52¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
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...
01:15¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR
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.
02:11Conformations of Cyclohexane
Cyclohexane does not exist in a planar form due to the high angle and torsional strain it would experience in the planar structure. Instead, it adopts non-planar chair and boat conformations.
The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal tetrahedral value,...
The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal tetrahedral value,...
02:06Newman Projections
Different notations are used to represent the three-dimensional structure of molecules on two-dimensional surfaces. One of the most commonly used representations is the dash-wedge formula. The dashed wedges, solid wedges, and the plane lines indicate the groups situated behind the plane, coming out of the plane, and in the plane, respectively.
The organic molecules rotate across the single bonds leading to numerous temporary three-dimensional structures of varying energy known as conformers.
The organic molecules rotate across the single bonds leading to numerous temporary three-dimensional structures of varying energy known as conformers.
02:18Conformations of Ethane and Propane
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 ethane, the...
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 ethane, the...
01:49Conserved Binding Sites
Many proteins’ biological role depends on their interactions with their ligands, small molecules that bind to specific locations on the protein known as ligand-binding sites. Ligand-binding sites are often conserved among homologous proteins as these sites are critical for protein function.
Binding sites are often located in large pockets, and if their location on a protein’s surface is unknown, it can be predicted using various approaches. The energetic method computationally analyses the...
Binding sites are often located in large pockets, and if their location on a protein’s surface is unknown, it can be predicted using various approaches. The energetic method computationally analyses the...