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Kinetic Screening of Nuclease Activity using Nucleic Acid Probes
Published on: November 1, 2019
La alta constante dieléctrica de la nucleasa estafilocócica está codificada en su arquitectura estructural
Garrett B Goh1, Bertrand García-Moreno E, Charles L Brooks
1Department of Chemistry, University of Michigan, 930 North University, Ann Arbor, Michigan 48109, USA.
Journal of the American Chemical Society
|November 17, 2011
Resumen
La nucleasa estafilocócica exhibe una constante dieléctrica intrínseca alta (20-30), no alterada significativamente por las mutaciones. Esta propiedad intrínseca, que surge de las fluctuaciones de la columna vertebral, explica los desplazamientos de pK observados en los residuos enterrados.
Área de la Ciencia:
- La biofísica es la biofísica.
- Estructura y dinámica de las proteínas.
- Biología computacional Biología computacional.
Sus antecedentes:
- Los residuos ionizables enterrados en las proteínas pueden exhibir valores de pK (a) significativamente alterados.
- Estudios anteriores sugirieron que se necesitaban altas constantes dieléctricas de proteínas (≥10) para explicar estos cambios, posiblemente debido a cambios estructurales locales.
Objetivo del estudio:
- Para calcular la constante dieléctrica de la nucleasa estafilocócica (Δ+PHS) y sus mutantes a partir de los primeros principios.
- Para investigar el origen de la alta constante dieléctrica aparente observada en los cálculos electrostáticos continuos.
Principales métodos:
- Utilizó la ecuación de Kirkwood-Fröhlich para los cálculos de la constante dieléctrica de los primeros principios.
- Se realizaron cálculos sobre la variante Δ+PHS de la nucleasa estafilocócica y las mutaciones de Lys-66, Asp-66 y Glu-66.
- Analizó la dependencia espacial de la constante dieléctrica alrededor del residuo 66.
Principales resultados:
- La nucleasa de estafilococo posee una constante dieléctrica naturalmente alta (20-30).
- Esta alta constante dieléctrica es en gran medida independiente de las mutaciones en el residuo 66 y la ionización del residuo.
- El microambiente alrededor del residuo 66 muestra una constante dieléctrica de aproximadamente 10, consistente con los cálculos previos del continuo.
Conclusiones:
- La constante dieléctrica alta intrínseca de la nucleasa estafilocócica se atribuye a las fluctuaciones de la columna vertebral inherentes a su estructura.
- Esta propiedad intrínseca proporciona una explicación alternativa para las constantes dieléctricas aparentemente altas necesarias en los modelos electrostáticos de continuo.
- Los hallazgos ofrecen nuevos conocimientos sobre la electrostática de las proteínas y el comportamiento de los residuos enterrados.
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