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Creación de un par de biocatalizadores estereocímicamente complementarios entre sí

Gavin J Williams¹, Thomas Woodhall, Lorna M Farnsworth

¹Astbury Centre for Structural Molecular Biology and School of Chemistry, University of Leeds, Leeds, LS2 9JT, United Kingdom.

Journal of the American Chemical Society

|December 15, 2006

Resumen

Los investigadores diseñaron variantes de N-Acetilneuraminic acid lyase (NAL) utilizando la evolución dirigida para superar la mala selectividad facial en la formación de enlaces carbono-carbono. Estos biocatalizadores complementarios permiten una síntesis altamente diastereoselectiva de los miméticos del ácido siálico, ampliando las aplicaciones de la química sintética.

Área de la Ciencia:

Biocatálisis y ingeniería de enzimas.
Química orgánica sintética y orgánica.
Síntesis estereoselectiva por síntesis.

Sus antecedentes:

La liasa de ácido N-acetilneuramínico (NAL) suele mostrar una selectividad facial limitada en la formación de enlaces carbono-carbono, lo que restringe su uso en la química sintética.
Las reacciones catalizadas por NAL existentes producen mezclas de productos diastereoméricos, lo que requiere métodos catalíticos mejorados para un control estereoquímico preciso.

Objetivo del estudio:

Diseñar variantes de NAL estereocímicamente complementarias para una mayor selectividad en la síntesis de miméticos del ácido siálico.
Para superar las limitaciones de la NAL de tipo silvestre para lograr una síntesis altamente diastereoselectiva de configuraciones específicas de productos.

Principales métodos:

Utilizó la evolución dirigida, incluida la PCR propensa a errores y la mutagénesis dirigida al sitio, guiada por el análisis estructural.
Se centra en la modificación de los residuos del sitio activo para alterar el resultado estereoquímico de las reacciones de aldol catalizadas por NAL.
Se desarrollaron variantes complementarias (E192N/T167G y E192N/T167V/S208V) con una alta selectividad para configuraciones alternativas de productos.

Principales resultados:

Se crearon variantes NAL con una selectividad de aproximadamente 50 veces para la escisión de productos de condensación con configuración 4S o 4R.
Logró una síntesis altamente diastereoselectiva (>98:2) de productos miméticos de ácido siálico con configuración 4S y 4R a partir de materiales de partida idénticos.
Se demostró que el NAL de tipo salvaje proporciona solo una favorabilidad cinética y termodinámica marginal para las configuraciones de producto deseadas.

Conclusiones:

Transformó una aldoasa no selectiva en un par de biocatalizadores complementarios con un control estereoquímico significativo.
Las variantes NAL diseñadas ofrecen una poderosa herramienta para la síntesis diastereoselectiva de imitadores del ácido siálico.
Los residuos críticos identificados se conservan, lo que sugiere que este enfoque se puede aplicar para desarrollar otros biocatalizadores para sintetizar moléculas biológicamente activas.

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