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Efectos de isótopos de disolventes en la transferencia de electrones de proteínas interfaciales en cristales y
Seong A Kang1, Kevin R Hoke, Brian R Crane
1Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
Journal of the American Chemical Society
|February 16, 2006
Resumen
La sustitución de óxido de deuterio (D2O) en los cristales de citocromo c peroxidasa (CcP) ralentiza la cinética de transferencia de electrones (ET). Este efecto D2O, observado tanto en estudios de cristal como de película, se atribuye al intercambio lento de protones o moléculas de disolvente que afectan las interacciones CcP-citocromo c.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología Estructural Biología estructural.
- Química Física es la química física.
Sus antecedentes:
- El citocromo c peroxidasa (CcP) y el citocromo c (yCc) son enzimas clave en la respiración celular.
- La transferencia de electrones (ET) entre CcP y yCc es crucial para su función.
- Comprender los factores que influyen en las tasas de ET es vital para los estudios bioquímicos y biofísicos.
Objetivo del estudio:
- Para investigar el impacto de la sustitución de óxido de deuterio (D2O) en la estructura y la cinética de transferencia de electrones de la levadura iso-1-citocromo c peroxidasa (ZnCcP) en complejo con levadura iso-1-citocromo c (yCc).
- Para aclarar el papel de D2O en la modulación de las interacciones proteína-proteína y las vías de transferencia de electrones.
Principales métodos:
- Cristalografía de rayos X de cristales de ZnCcP-yCc cultivados con D2O para determinar estructuras de alta resolución.
- Análisis espectroscópico para medir la transferencia de electrones (ET) y el apagado del estado excitado triple.
- Voltametría de película de proteínas para evaluar las tasas de ET en películas yCc en superficies de electrodos.
Principales resultados:
- Los cristales cultivados con D2O se difractaron a una mayor resolución (1.7 Å) y exhibieron un empaque diferente en comparación con los cristales cultivados con H2O.
- Dos moléculas de ZnCcP unidas a una yCc, con ET observado desde ZnCcP hasta Fe(III) yCc (k(e) = 220 s−1).
- La sustitución de D2O ralentizó significativamente la recombinación térmica ET en cristales y la transferencia de electrones en películas yCc, con efectos isotópicos observados.
Conclusiones:
- La sustitución de D2O perturba las interacciones y la transferencia de electrones entre yCc y CcP o las películas de electrodos.
- Los efectos observados se atribuyen al intercambio lento de protones o moléculas de disolvente, lo que lleva a cambios estructurales sutiles.
- Estos hallazgos ponen de relieve la sensibilidad de los procesos de transferencia de electrones al entorno isotópico.
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