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Evidencia para la catálisis mediada por radicales por HppE: un estudio utilizando análogos de sustratos de

Hui Huang¹, Wei-chen Chang, Pei-Jing Pai

¹Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712, USA.

Journal of the American Chemical Society

|September 26, 2012

Resumen

(S) 2-Hydroxypropylphosphonic acid epoxidase (HppE) utiliza intermediarios radicales para la biosíntesis de la fosfomicina. (S) 2-Hydroxypropylphosphonic acid epoxidase (HppE) utiliza intermediarios radicales para la biosíntesis de la fosfomycina. (S) 2-Hydroxypropylphosphonic acid epoxidase (HppE) utiliza intermediarios radicales para la biosíntesis de la fosfomycina. (S) 2-Hydroxypropylphosphonic acid epoxidase (HppE) utiliza intermediarios radicales para la biosíntesis de la fosfomycina. Los estudios revelan un radical centrado en C2 en la oxidación de (R) -HPP, lo que proporciona una visión mecánica clave de esta enzima de hierro inusual.

Área de la Ciencia:

La bioquímica es la bioquímica.
Enzimología Enzimología.
Química orgánica es la química orgánica.

Sus antecedentes:

La enzima (S)-2-hidroxipropilfosfónica ácido epoxidasa (HppE) es crucial para la biosíntesis del antibiótico fosfomicina.
HppE, una enzima de hierro mononuclear inusual, cataliza la epoxidación oxidativa del ácido (S)-2-hidroxipropilfosfónico ((S) -HPP).
HppE también procesa el (R) -isómero, (R) -2-hidroxipropilfosfónico ácido ((R) -HPP), en 2-oxo-propilfosfónico ácido.

Objetivo del estudio:

Para dilucidar los mecanismos de reacción de las oxidaciones catalizadas por HppE.
Investigar la participación de los radicales intermedios en la actividad del HppE.
Para sondear la especificidad del sustrato y las vías catalíticas de HppE.

Principales métodos:

Síntesis de análogos de sustratos de relojes radicales que contienen ciclopropilo y metilenociclopropilo.
Ensayos enzimáticos que utilizan estos análogos para estudiar la actividad de HppE.
Análisis de productos de reacción para determinar los mecanismos de las enzimas.

Principales resultados:

HppE convirtió eficientemente los análogos que contienen ciclopropilo en productos de epóxido ((S) -isómero) y cetona ((R) -isómero).
Los análogos del metilenociclopropilo inactivaron rápidamente el HppE, lo que indica una rápida apertura del anillo desencadenada por los radicales.
La evidencia experimental apoya un radical intermedio centrado en C2 con una vida útil de nanosegundos en la oxidación (R) -HPP.

Conclusiones:

El estudio proporciona la primera evidencia experimental de un radical intermedio centrado en C2 en la oxidación HppE-catalizada (R) -HPP.
Los análogos del reloj radical exploran efectivamente los mecanismos de las reacciones enzimáticas inusuales de HppE.
Los hallazgos avanzan en la comprensión de la catálisis de la enzima del hierro mononuclear y la biosíntesis de la fosfomicina.

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