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Conocimiento mecanicista sobre el papel de la estabilización del estado de transición en la ciclofilina A
Donald Hamelberg1, J Andrew McCammon
1Department of Chemistry, Georgia State University, Atlanta, Georgia 30302-4098, USA.
Journal of the American Chemical Society
|January 9, 2009
Resumen
Las peptidilprolyl cis-trans isomerasas (PPIases) catalizan cambios cruciales en la conformación de las proteínas. Las simulaciones de dinámica molecular revelan que la ciclofilina A estabiliza el estado de transición a través de enlaces de hidrógeno, mejorando la catálisis.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Molecular Biología Molecular
- Enzimología Enzimología.
Sus antecedentes:
- Las peptidil prolyl cis-trans isomerasas (PPIases) son enzimas vitales que catalizan la isomerización de los enlaces de prolina imida.
- Esta isomerización regula la conformación de las proteínas y las vías de señalización celular.
- Los métodos experimentales actuales carecen de detalles atómicos para los mecanismos de la PPIasa.
Objetivo del estudio:
- Para dilucidar el mecanismo atomístico de la isomerización cis-trans mediada por la PPIasa.
- Para detallar el papel catalítico de la ciclofilina A en este proceso.
- Para investigar las interacciones de sustrato dentro del sitio activo de la enzima.
Principales métodos:
- Se emplearon simulaciones de dinámica molecular acelerada con disolvente explícito.
- Las simulaciones analizaron tanto la isomerización libre como la catalizada por ciclofilina A.
- Se examinaron las interacciones clave y los cambios conformacionales a nivel atómico.
Principales resultados:
- La catalización de la ciclofilina A involucra principalmente la estabilización del estado de transición a través de enlaces de hidrógeno.
- La enzima se une preferentemente al estado de transición sobre los isómeros cis o trans.
- La estabilidad del complejo enzima-sustrato se correlaciona con las interacciones que involucran un residuo de arginina conservado.
Conclusiones:
- La catálisis es impulsada por interacciones favorables con el estado de transición, en particular los enlaces de hidrógeno.
- El perfil de interacción del sustrato dicta la estabilidad del complejo enzima-sustrato.
- La isomerización se produce a través de una rotación predominantemente unidireccional del oxígeno carbonilo.
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