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La descomposición no enzimática de las guanidinas y amidinas

Charles A Lewis¹, Richard Wolfenden

¹Department of Biochemistry and Biophysics, University of North Carolina , Chapel Hill, North Carolina 27599, United States.

Journal of the American Chemical Society

|December 24, 2013

Resumen

Este estudio detalla las tasas de descomposición de los derivados de guanidina y amidina en el agua. Las enzimas como la arginasa y la agmatinasa aceleran significativamente esta hidrólisis, revelando conocimientos sobre la catálisis biológica.

Área de la Ciencia:

La bioquímica es la bioquímica.
La cinética química es la cinética química.

Sus antecedentes:

Los derivados de guanidina y amidina son cruciales en los sistemas biológicos.
Comprender sus mecanismos de descomposición es vital para la bioquímica.

Objetivo del estudio:

Para determinar las tasas de descomposición y los mecanismos de los derivados de guanidina y amidina en solución acuosa.
Para cuantificar las mejoras de velocidad proporcionadas por enzimas específicas.

Principales métodos:

Tasas de reacción examinadas a temperaturas elevadas.
Utilizó la ecuación de Arrhenius para la extrapolación de la temperatura ambiente.
Investigó la influencia del pH en las tasas de descomposición.

Principales resultados:

La descomposición de la metilguanidina y 1,1,3,3-tetrametilguanidina se produce por hidrólisis.
La N-metilguanidina es significativamente más estable que la acetamidina, la urea o la acetamida a un pH de 7.
La arginasa, la agmatinasa y la arginina deiminasa exhiben aceleraciones masivas de la velocidad (10^12-10^14 veces).

Conclusiones:

Los mecanismos de hidrólisis enzimática difieren: la arginasa/agmatinasa utiliza el ataque de agua mediada por metales, mientras que la arginina deiminasa utiliza el ataque de cisteína en el sitio activo.
Las enzimas mejoran drásticamente las tasas de hidrólisis del sustrato.
La hidrólisis es la principal vía de descomposición para estos compuestos.

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