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Diferentes mecanismos de reacción para las dihidrofolato reductasas mesófilas y termófilas
E Joel Loveridge1, Enas M Behiry, Richard S Swanwick
1School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, UK.
Journal of the American Chemical Society
|May 8, 2009
Resumen
Los efectos del isótopo cinético del disolvente revelan mecanismos distintos para la dihidrofolato reductasa de E. coli (EcDHFR) y la dihidrofolato reductasa marítima de Thermotoga (TmDHFR). TmDHFR es el nombre de la banda.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Enzimología Enzimología.
- Biología Estructural Biología estructural.
Sus antecedentes:
- La dihidrofolato reductasa (DHFR) es una enzima crucial en el metabolismo del folato.
- La comparación entre la DHFR mesofílica (E. coli) y la termofílica (Thermotoga maritima) ofrece información sobre la adaptación de las enzimas.
- Comprender los mecanismos enzimáticos es clave para el desarrollo de fármacos y la biotecnología.
Objetivo del estudio:
- Para aclarar las diferencias mecánicas entre el DHFR monomérico de E. coli (EcDHFR) y el DHFR marítimo de Thermotoga dimérico (TmDHFR).
- Para investigar el papel de la estructura de la enzima y el pH en los mecanismos catalíticos utilizando los efectos del isótopo cinético del disolvente.
Principales métodos:
- Los efectos del isótopo cinético del disolvente (SKIEs) se midieron tanto para EcDHFR como para TmDHFR.
- La cinética de las enzimas se analizó en diferentes condiciones de pH.
Principales resultados:
- EcDHFR exhibe un mecanismo de transferencia gradual de protones e hidruro.
- TmDHFR muestra un mecanismo concertado de transferencia de protones e hidruro.
- El mecanismo de TmDHFR se asemeja a EcDHFR a pH elevado, lo que sugiere que las restricciones estructurales impactan en la modulación del sustrato.
Conclusiones:
- La estructura de la enzima influye significativamente en el mecanismo catalítico y la reactividad del sustrato.
- La estructura dimérica de TmDHFR, aunque confiere termostabilidad, restringe la modulación del sitio activo en comparación con el EcDHFR monomérico.
- Las diferencias mecánicas destacan las adaptaciones evolutivas en las enzimas DHFR.
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