Video Experimental Relacionado
Updated: Jun 17, 2026
09:42
Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes
Published on: January 16, 2016
Efectos del disolvente en la catálisis por Escherichia coli dihidrofolato reductasa
E Joel Loveridge1, Lai-Hock Tey, Rudolf K Allemann
1School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK.
Journal of the American Chemical Society
|January 6, 2010
Resumen
La constante dieléctrica del medio de reacción, no la viscosidad, influye en la velocidad de transferencia de hidruro catalizada por la dihidrofolato reductasa (DHFR). Los cambios en el disolvente no afectaron el efecto del isótopo cinético ni su dependencia de la temperatura.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- La cinética de las enzimas.
- Dinámica de las proteínas Dinámica de las proteínas
Sus antecedentes:
- La dihidrofolato reductasa (DHFR) cataliza la transferencia de hidruro a través del túnel de hidrógeno acoplado al medio ambiente.
- Se cree que los movimientos de las proteínas controlan la unión de sustrato/cofactor y modulan el ancho de la barrera de activación, influyendo en las tasas de reacción.
- Los cambios en la composición del medio de reacción pueden perturbar los movimientos de las proteínas.
Objetivo del estudio:
- Investigar el efecto de la composición del medio de reacción en la cinética de la transferencia de hidruro catalizada por DHFR.
- Para determinar si la constante dieléctrica o la viscosidad del medio impactan en la catálisis enzimática.
- Para explorar la relación entre las propiedades del disolvente y el mecanismo de transferencia de hidruro.
Principales métodos:
- Los parámetros cinéticos de Escherichia coli DHFR se midieron en presencia de varios cosolventes y cosolutos.
- Se analizaron los efectos cinéticos de los isótopos y su dependencia de la temperatura.
- Comparación de los resultados con estudios previos sobre DHFR de Thermotoga maritima.
Principales resultados:
- La constante dieléctrica del medio de reacción afectó significativamente la velocidad de reacción, mientras que la viscosidad no lo hizo.
- Ni el efecto del isótopo cinético primario ni su dependencia de la temperatura fueron alterados por las propiedades del disolvente a granel.
- El efecto del disolvente en la dependencia de la temperatura del efecto del isótopo cinético para E. coli DHFR presentó desafíos para los modelos existentes.
Conclusiones:
- La catálisis enzimática por DHFR es sensible a las propiedades dieléctricas del medio circundante.
- Los hallazgos sugieren que, si bien los movimientos de largo alcance pueden no ser el único determinante, las vibraciones de corto alcance o los subestados conformacionales podrían desempeñar un papel en la catálisis de DHFR.
- Se necesitan más investigaciones para dilucidar completamente el mecanismo de los efectos del disolvente en la transferencia de hidruro catalizado por DHFR.
Más Videos Relacionados
12:08Catalytic Reactions at Amine-Stabilized and Ligand-Free Platinum Nanoparticles Supported on Titania During Hydrogenation of Alkenes and Aldehydes
Published on: June 24, 2022
12:08Monitoring the Reductive and Oxidative Half-Reactions of a Flavin-Dependent Monooxygenase using Stopped-Flow Spectrophotometry
Published on: March 18, 2012
Videos de Conceptos Relacionados
01:22Heterogeneous Catalysis
Heterogeneous catalysis involves a catalyst in a different phase from the reactants. It is a process where the catalyst and the reactants are in distinct phases, typically solid and gas or liquid.Most heterogeneous catalysts are metals, metal oxides, or acids. The list includes transition metals like iron (Fe), cobalt (Co), nickel (Ni), palladium (Pd), platinum (Pt), chromium (Cr), manganese (Mn), tungsten (W), silver (Ag), and copper (Cu). These metals possess partially vacant d orbitals that...
02:12Solvating Effects
An understanding of the solvating effect helps rationalize the relation between solvation and acidity of the compound. In addition, this also explains the relative stability of conjugate bases for compounds with different pKa values. This lesson details, in-depth, the principle of solvating effects. The strength of an acid and the stability of its corresponding conjugate base are determined using pKa values. This observed relationship is a consequence of solvation, which is the interaction...
02:50Catalysis
The presence of a catalyst affects the rate of a chemical reaction. A catalyst is a substance that can increase the reaction rate without being consumed during the process. A basic comprehension of a catalysts’ role during chemical reactions can be understood from the concept of reaction mechanisms and energy diagrams.
01:27Catalysis
Catalysis influences the rate of chemical reactions by providing an alternative reaction pathway with lower activation energy. A catalyst speeds up a reaction, but it is not consumed during the process. The fundamental principle of catalysis is the ability of a catalyst to alter the reaction mechanism, often introducing a more efficient pathway than the uncatalyzed process.In a catalyzed reaction, the catalyst participates directly in the reaction mechanism. It interacts with reactants to form...
01:29Leveling Effect
In acid-base chemistry, the leveling effect refers to the limitation imposed by the solvent on the strength of acids and bases in solution. When a base stronger than the solvent's conjugate base is used, it deprotonates the solvent until the base is entirely consumed, making it ineffective against weaker acids. Conversely, an acid stronger than the solvent's conjugate acid protonates the solvent until the acid is depleted, rendering it ineffective against weaker bases. Essentially, the solvent...
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...