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Una mutación en un solo sitio (F429H) convierte la enzima CYP 2B4 en una hemooxigenasa: un estudio QM/MM
Dandamudi Usharani1, Costantino Zazza, Wenzhen Lai
1Institute of Chemistry and the Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel.
Journal of the American Chemical Society
|February 24, 2012
Resumen
La mutación del citocromo P450 2B4 (CYP 2B4) a F429H altera la escisión del enlace O-OH. La enzima mutante exhibe actividad similar a la hemooxigenasa a través de la escisión homolítica, lo que permite una eficiente mesohidroxilación.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Enzimología Enzimología.
- Química computacional es la química computacional.
Sus antecedentes:
- Las enzimas del citocromo P450 (CYP) son cruciales para el metabolismo y la biosíntesis de los fármacos.
- Comprender los mecanismos de desactivación de las enzimas es vital para el diseño de fármacos y la ingeniería enzimática.
- La mutación Phe429 a His en el CYP 2B4 conduce a una pérdida de la actividad enzimática normal.
Objetivo del estudio:
- Investigar el mecanismo molecular detrás de la desactivación de la CYP 2B4 tras la mutación de Phe429 a His.
- Para dilucidar la vía de activación del enlace O-OH en el intermedio (Fe3+) OOH) - del mutante F429H.
- Comprender cómo la mutación confiere características similares a las de la hemooxigenasa al CYP 2B4.4.
Principales métodos:
- Se emplearon cálculos mecánicos cuánticos / mecánicos moleculares (QM / MM).
- El estudio se centró en la activación de los enlaces O-OH del intermediario (Fe3+) OOH).
- Se realizó un análisis de las interacciones de enlaces de hidrógeno y las estructuras electrónicas.
Principales resultados:
- El mutante F429H del CYP 2B4 exhibe una escisión homolítica de enlaces O-OH, en contraste con la escisión heterolítica en la enzima de tipo salvaje.
- His429 forma un enlace adicional de hidrógeno NH---S con el ligando de cisteína, que, junto con la presencia de sustrato, promueve la escisión homolítica.
- Un grupo Thr302/agua facilita la orientación del radical hidroxilo (OH•) para una eficiente mesohidroxilación.
Conclusiones:
- La mutación Phe429 a His altera fundamentalmente el mecanismo catalítico del CYP 2B4, desplazándolo hacia la escisión homolítica de enlaces O-OH.
- La enzima mutante imita la actividad de la hemooxigenasa debido a la unión específica de hidrógeno y las interacciones del sustrato.
- Estos hallazgos proporcionan información sobre la desactivación de enzimas y el diseño de nuevos biocatalizadores.
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