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Interconversión de (S) -glutamato y (2S,3S) -3-metilaspartato: un reordenamiento distintivo del esqueleto de carbono
S D Wetmore1, D M Smith, B T Golding
1Contribution from the Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia.
Journal of the American Chemical Society
|August 17, 2001
Resumen
Este estudio utiliza métodos computacionales avanzados para explorar cómo la mutasa del glutamato dependiente de la vitamina B 12 facilita la conversión del (S) glutamato en 3-metilaspartato. Los hallazgos sugieren que la generación de radicales y la transferencia de protones son pasos clave en esta reacción enzimática.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Química computacional es la química computacional.
- Enzimología Enzimología.
Sus antecedentes:
- La enzima glutamato mutasa, dependiente de la vitamina B, cataliza la interconversión del (S) -glutamato y el (2S,3S) -3-metilaspartato.
- Comprender el mecanismo de esta reacción es crucial para elucidar las transformaciones enzimáticas basadas en radicales.
Objetivo del estudio:
- Para investigar el mecanismo de reacción de la mutasa glutamato dependiente de B(12) utilizando cálculos orbitales moleculares ab initio de alto nivel.
- Explorar el papel de la coenzima-B(12) en la activación del sustrato, la formación de productos y la generación de radicales.
- Proporcionar soporte computacional para hallazgos experimentales con respecto a la vía de fragmentación-recombinación.
Principales métodos:
- Se emplearon cálculos de orbitales moleculares ab initio de alto nivel.
- Los parámetros de resonancia paramagnética de electrones (EPR) se calcularon para apoyar la participación de los radicales.
- Se utilizó un modelo computacional que incluía sustitutos de aminoácidos y ácidos carboxílicos para calcular la barrera de reordenamiento.
Principales resultados:
- Los parámetros de resonancia paramagnética de electrones calculados se alinean con la evidencia experimental de radicales derivados del sustrato.
- La altura calculada de la barrera de reordenamiento soporta una vía de fragmentación-recombinación para la reacción.
- Los resultados computacionales sugieren que la enzima facilita el reordenamiento a través de procesos de transferencia de protones que influyen en el estado de protonación del grupo migratorio.
Conclusiones:
- La coenzima-B(12) probablemente juega un papel en la activación del sustrato y la formación de productos a través de la generación de radicales.
- La interconversión de (S) -glutamato y 3-metilaspartato se produce a través de una vía de fragmentación-recombinación.
- La catálisis enzimática puede implicar mecanismos de transferencia de protones para controlar el estado de protonación de grupos moleculares clave.
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