Video Experimental Relacionado
Updated: May 29, 2026
14:55
Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
La RMN de estado sólido detectada por protones revela redes polares intramembranares en una proteorhodopsina de
Meaghan E Ward1, Lichi Shi, Evelyn Lake
1Department of Physics and Biophysics Interdepartmental Group, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
Journal of the American Chemical Society
|September 17, 2011
Resumen
La RMN de alta resolución reveló regiones expuestas al disolvente de la proteorhodopsina (PR), una bomba de protones de membrana. Helix G, que contiene residuos clave y Lys231, es accesible, apoyando su papel en el transporte de protones.
Área de la Ciencia:
- Biología Estructural Biología estructural.
- La biofísica es la biofísica.
- Proteínas de membrana Proteínas de membrana.
Sus antecedentes:
- La proteorhodopsina (PR) es una bomba de protones de membrana integral de siete hélices.
- Comprender la accesibilidad del disolvente del PR es crucial para elucidar su mecanismo de transporte de protones.
Objetivo del estudio:
- Para investigar las regiones expuestas al disolvente de la proteorhodopsina utilizando técnicas avanzadas de RMN.
- Para identificar los residuos involucrados en la translocación de protones y relacionarlos con la estructura y función de PR.
Principales métodos:
- Espectroscopia multidimensional de RMN con detección de protones de alta resolución y detección de protones.
- Preparación de muestras de PR utilizando medio deuterado y intercambio de protones.
- Espectroscopia tridimensional de correlación de desplazamiento químico detectado por protones para la asignación de resonancia.
Principales resultados:
- Resonancias identificadas y asignadas para los residuos expuestos al disolvente en PR.
- La mayoría de los residuos accesibles se encuentran en la interfaz de la membrana, con notables excepciones en la hélice G.
- Helix G, que contiene Lys231 y residuos polares conservados, mostró un intercambio H/D significativo, lo que indica la accesibilidad al disolvente.
Conclusiones:
- La accesibilidad del disolvente de la hélice G apoya la hipótesis de una cavidad hidrófila expuesta transitoriamente.
- Esta cavidad, potencialmente revestida por la hélice G, puede ser parte de la vía de conducción de protones.
- Los datos de RMN proporcionan información sobre las bases estructurales del bombeo de protones en la proteorhodopsina.
Videos de Conceptos Relacionados
01:26Insertion of Single-pass Transmembrane Proteins in the RER
Integral membrane proteins are proteins adhered to the lipid bilayer of a cell organelle or membrane. They can be of two types: transmembrane integral proteins that span the lipid bilayer and monotopic proteins that are attached to either side of the membrane but do not pass through it.
Integral transmembrane proteins possess transmembrane and extra membrane domains. The transmembrane domains are primarily made of 20-25 hydrophobic amino acids arranged in a helical secondary confirmation. These...
Integral transmembrane proteins possess transmembrane and extra membrane domains. The transmembrane domains are primarily made of 20-25 hydrophobic amino acids arranged in a helical secondary confirmation. These...
01:33Proteomics
A proteome is the entire set of proteins that a cell type produces. We can study proteomes using the knowledge of genomes because genes code for mRNAs, and the mRNAs encode proteins. Although mRNA analysis is a step in the right direction, not all mRNAs are translated into proteins.
Proteomics is the study of proteomes' function. It involves the large-scale systematic study of the proteome to denote the protein complement expressed by a genome. Scientist Mark Wilkins coined the term proteomics...
Proteomics is the study of proteomes' function. It involves the large-scale systematic study of the proteome to denote the protein complement expressed by a genome. Scientist Mark Wilkins coined the term proteomics...
01:09Multi-pass Transmembrane Proteins and β-barrels
In multi-pass transmembrane proteins, the polypeptide chain crosses the membrane more than once. The transmembrane polypeptide chain either forms an α-helix or β-strand structure. α-Helix containing multi-pass transmembrane proteins are ubiquitous, whereas β-strand containing ones are mainly found in gram-negative bacteria, mitochondria, and chloroplasts.
α-Helix containing multi-pass transmembrane proteins
Multi-pass transmembrane proteins such as G-protein-linked receptors (GPCRs) and...
α-Helix containing multi-pass transmembrane proteins
Multi-pass transmembrane proteins such as G-protein-linked receptors (GPCRs) and...
01:29Insertion of Multi-pass Transmembrane Proteins in the RER
The rough ER membrane synthesizes, assembles, and embeds transmembrane proteins in diverse topologies. These proteins function as transporters or channels and can remain in the ER membrane or are sent to the Golgi complex, lysosome, and cell membrane.
The multipass transmembrane proteins are the type IV integral membrane proteins with multiple topogenic sequences determining their spatial arrangement in the ER membrane. Nearly all multipass proteins lack a cleavable signal sequence and use...
The multipass transmembrane proteins are the type IV integral membrane proteins with multiple topogenic sequences determining their spatial arrangement in the ER membrane. Nearly all multipass proteins lack a cleavable signal sequence and use...
01:07Proton (¹H) NMR: Chemical Shift
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 in a...
Absorption signals of all the protium nuclei in a...
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...