Video Experimental Relacionado
Updated: Jun 19, 2026
07:26
Metabolic Pathway Confirmation and Discovery Through 13C-labeling of Proteinogenic Amino Acids
Published on: January 26, 2012
Asignación de las correlaciones metilo de Ile, Leu y Val en sistemas supra-moleculares: una aplicación a la
Algirdas Velyvis1, Howard K Schachman, Lewis E Kay
1Department of Biochemistry, University of Toronto, Toronto, ON, Canada M5S 1A8.
Journal of the American Chemical Society
|October 29, 2009
Resumen
Los investigadores desarrollaron métodos para asignar grupos metilo en grandes complejos proteicos como la aspartato transcarbamoilasa (ATCase). Las técnicas de combinación asignaron el 86% de los grupos metilo, revelando cambios estructurales en la unión al ATP.
Área de la Ciencia:
- Biología Estructural Biología estructural.
- La bioquímica es la bioquímica.
- La biofísica es la biofísica.
Sus antecedentes:
- La asignación de grupos metilo en grandes complejos de proteínas utilizando Methyl-TROSY (espectroscopia optimizada de relajación transversal) es un desafío.
- Comprender la estructura y la dinámica de los complejos de proteínas supramoleculares es crucial para descifrar las funciones biológicas.
Objetivo del estudio:
- Presentar y comparar enfoques complementarios para la asignación de grupos metilo en espectros Metil-TROSY de grandes complejos proteicos.
- Aplicar estos métodos a la enzima aspartato transcarbamoylasa (ATCase) e investigar su respuesta estructural a la unión de nucleótidos.
Principales métodos:
- Transferencia de asignación desde fragmentos más pequeños utilizando un enfoque de "divide y vencerás".
- Transferencia de asignación a través de la espectroscopia de intercambio.
- Generar asignaciones utilizando desplazamientos de pseudocontacto con sondas paramagnéticas.
Principales resultados:
- El método "divide y vencerás" asignó aproximadamente el 60% de los grupos metilo en ATCase.
- La combinación de todos los métodos logró asignaciones para el 86% de los grupos metilo, proporcionando extensas sondas de estructura y dinámica.
- El análisis de los cambios de desplazamiento químico tras la titulación de ATP reveló perturbaciones significativas en las colas N-terminales de la cadena reguladora.
Conclusiones:
- Una combinación de métodos complementarios mejora significativamente la asignación del grupo metilo en grandes complejos proteicos.
- El estudio proporciona la primera evidencia de perturbaciones estructurales en las cadenas reguladoras N-terminales de ATCase tras la unión de nucleótidos.
- Estos hallazgos ofrecen información sobre el mecanismo de regulación alostérica de ATCase.
Más Videos Relacionados
Videos de Conceptos Relacionados
01:19Allosteric Proteins-ATCase
Binding sites linkages can regulate a protein's function. For example, enzyme activity is often regulated through a feedback mechanism where the end product of the biochemical process serves as an inhibitor.
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis pathway,...
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis pathway,...
00:49Ligand Binding and Linkage
Allosteric proteins have more than one ligand binding site; the binding of a ligand to any of these sites influences the binding of ligands to the other sites. When a protein is allosteric, its binding sites are called coupled or linked. In the case of enzymes, the site that binds to the substrate is known as the active site and the other site is known as the regulatory site. When a ligand binds to the regulatory site, this leads to conformational changes in the protein that can influence the...
01:20¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
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...
01:15Mass Spectrometry of Amines
In mass spectroscopy, amines undergo fragmentation to give parent ions with odd molecule weights. This observed mass spectrum follows the nitrogen rule; a molecule with an odd number of nitrogen atoms produces a molecular ion with an odd molecular weight. Amines undergo fragmentation through α cleavage, producing nitrogen-containing cations—iminium ions—and alkyl radicals. Mass spectra of aromatic and cyclic aliphatic amines exhibit strong molecular ion peaks, but acyclic aliphatic amines show...
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.
02:26tRNA Activation
Aminoacyl-tRNA synthetases are present in both eukaryotes and bacteria. Though eukaryotes have 20 different aminoacyl-tRNA synthetases to couple to 20 amino acids, many bacteria do not have genes for all of these aminoacyl-tRNA synthetases. Despite this, they still use all 20 amino acids to synthesize their proteins. For instance, some bacteria do not have the gene encoding the enzyme that couples glutamine with its partner tRNA. In these organisms, one enzyme adds glutamic acid to all of the...