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Perspectivas sobre el origen de la catálisis en la glicina N-metiltransferasa a partir de modelos computacionales
Katarzyna Świderek1,2, Iñaki Tuñón3, Ian H Williams2
1Departament de Química Física i Analítica ; Universitat Jaume I , 12071 Castellón , Spain.
Journal of the American Chemical Society
|February 21, 2018
Resumen
Se debate el origen de la catálisis enzimática. Este estudio muestra la glicina N-metiltransferasa
Área de la Ciencia:
- La bioquímica
- Química computacional
- Enzimología
Sus antecedentes:
- Todavía se debaten los mecanismos precisos que subyacen a la catálisis enzimática.
- La glicina N-metiltransferasa (GNMT) juega un papel crucial en el metabolismo del grupo metilo.
- La comprensión de la dinámica del sitio activo de la enzima es clave para dilucidar la eficiencia catalítica.
Objetivo del estudio:
- Investigar el papel de la compresión del sitio activo frente a la electrostática en la catálisis de GNMT.
- Examinar teóricamente la reacción de transferencia de metilo SN2 en GNMT y sus mutantes.
- Para conciliar los hallazgos computacionales con las observaciones experimentales de los efectos de los isótopos cinéticos.
Principales métodos:
- Estudio teórico de la mecánica cuántica y molecular.
- Utilizado Semiempírico (AM1) y DFT (M06-2X) para la región QM.
- Utiliza campos de fuerza OPLS-AA y TIP3P para entornos de proteínas y disolventes.
Principales resultados:
- Las energías libres de activación computarizadas y los efectos de isótopos cinéticos (KIEs) se alinean bien con los datos experimentales.
- Las mutaciones no alteraron significativamente la distancia donante-acceptora de metilo (DAD), refutando la hipótesis de compresión.
- Las propiedades electrostáticas del sitio activo se correlacionan fuertemente con la actividad catalítica observada y las variaciones de KIE.
Conclusiones:
- La compresión enzimática no es el factor principal de las variaciones KIE observadas en GNMT.
- Las interacciones electrostáticas dentro del sitio activo son críticas para modular la actividad catalítica de GNMT.
- La plasticidad enzimática amortigua efectivamente el impacto de las mutaciones, lo que lleva a cambios sutiles en la reactividad y las KIE.
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