Video Experimental Relacionado
Updated: Jul 20, 2026
11:01
Application of Stopped-flow Kinetics Methods to Investigate the Mechanism of Action of a DNA Repair Protein
Published on: March 31, 2010
Las sintasas de pseudouridina: revisando un mecanismo que parecía establecido
Christopher J Spedaliere1, Joy M Ginter, Murray V Johnston
1Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA.
Journal of the American Chemical Society
|October 8, 2004
Resumen
Los estudios mecánicos utilizando ARN de 5-fluorouridina (f 5U) revelan que la hidrólisis de ésteres no está involucrada en la actividad de la pseudouridina sintasa TruB. Este hallazgo desafía las interpretaciones anteriores del mecanismo enzimático.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Molecular Biología Molecular
- Enzimología Enzimología.
Sus antecedentes:
- Las sintasas de la pseudouridina catalizan la isomerización de la uridina a la pseudouridina en el ARN.
- El ARN de 5-fluorouridina (f 5U) se ha empleado como una sonda mecanicista para estas enzimas.
- Estudios anteriores sugirieron la hidrólisis de éster de un complejo covalente que involucra un residuo de ácido aspártico.
Objetivo del estudio:
- Para investigar el mecanismo de la pseudouridina sintasa TruB utilizando el etiquetado de agua [18O].
- Para determinar si se produce la hidrólisis de ésteres durante la conversión enzimática de la uridina en pseudouridina.
- Reevaluar el mecanismo de adición propuesto por Michael.
Principales métodos:
- Ensayos enzimáticos utilizando el ARN [f 5U] como sustrato.
- Estudios de etiquetado isotópico con [18O] agua.
- Análisis de productos de reacción para identificar la fuente de los átomos de oxígeno.
Principales resultados:
- Los estudios de etiquetado con [18O] agua descartaron la hidrólisis de ésteres en la pseudouridina sintasa TruB.
- El residuo catalítico de ácido aspártico en TruB no se etiquetó con 18O.
- El grupo hidroxilo en el producto hidratado de f 5U se originó directamente del disolvente, no de la hidrólisis de ésteres.
Conclusiones:
- Los resultados no apoyan la hidrólisis de ésteres como un paso en la reacción de pseudouridilación catalizada por TruB.
- Los hallazgos desafían la interpretación de que los productos hidratados de f 5U apoyan un mecanismo de adición de Michael en TruB.
- Se propone una hipótesis para explicar los diferentes comportamientos de las sintasas de pseudouridina con el ARN [f 5U].
Videos de Conceptos Relacionados
02:37Restarting Stalled Replication Forks
DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the minichromosome maintenance (MCM) helicase and other factors such as Cdc45 and the associated GINS complex.The unwound single strands are protected by replication protein A (RPA) until DNA polymerase starts synthesizing DNA at the 5’ end of the strand in the same direction as the replication fork. To prevent the replication fork from falling apart, a...
02:53Conservative Site-specific Recombination and Phase Variation
Because the DNA segments are cut and reorganized in a direction-specific manner, site-specific recombination has emerged as an efficient genetic engineering technique. Flippase and Cyclization recombinases or Flp and Cre, respectively, are two members of the tyrosine recombinase family derived from bacteriophages, that are used to mediate site-specific DNA insertions, deletions, and targeted expression of proteins in mammalian cell lines.
The recognition sites for Cre recombinase called LoxP...
The recognition sites for Cre recombinase called LoxP...
01:13Introduction to Mechanisms of Enzyme Catalysis
For many years, scientists thought that enzyme-substrate binding took place in a simple "lock-and-key" fashion. This model stated that the enzyme and substrate fit together perfectly in one instantaneous step. However, current research supports a more refined view scientists call induced fit. The induced-fit model expands upon the lock-and-key model by describing a more dynamic interaction between enzyme and substrate. As the enzyme and substrate come together, their interaction causes a mild...
01:13Introduction to Mechanisms of Enzyme Catalysis
For many years, scientists thought that enzyme-substrate binding took place in a simple "lock-and-key" fashion. This model stated that the enzyme and substrate fit together perfectly in one instantaneous step. However, current research supports a more refined view scientists call induced fit. The induced-fit model expands upon the lock-and-key model by describing a more dynamic interaction between enzyme and substrate. As the enzyme and substrate come together, their interaction causes a mild...
01:27Transducer Mechanism: Enzyme-Linked Receptors
Enzyme-linked receptors are cell-surface receptors acting as an enzyme or associating with an enzyme intracellularly. They make excellent drug targets. Drugs can bind to the extracellular ligand-binding domain or directly affect their enzymatic domain and alter their activity.
Major types that are helpful drug targets include:
Major types that are helpful drug targets include:
01:30Production of Pharmaceuticals
Industrial insulin production uses genetically engineered E. coli expressing a proinsulin gene controlled by a tryptophan promoter and containing a methionine linker for later cleavage. The cells also carry ampicillin resistance for selective growth. Seed cultures are stored at −80 °C and production begins by thawing a small amount to inoculate starter cultures, which are progressively scaled to a 50,000-L bioreactor. In the bioreactor, E. coli grow in nutrient-rich media under sterile, tightly...