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Los efectos isotópicos de unión a la glucosa en el complejo ternario de la hexokinasa cerebral demuestran un alivio
Brett E Lewis1, Vern L Schramm
1Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA.
Journal of the American Chemical Society
|April 17, 2003
Resumen
Los efectos isotópicos revelan interacciones de unión de glucosa con la hexokinasa cerebral humana. La unión de nucleótidos altera los contactos enzimáticos en posiciones específicas de glucosa, lo que afecta las interacciones enzima-sustrato.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- La cinética de las enzimas.
- Biología estructural Biología estructural.
Sus antecedentes:
- Los efectos de los isótopos proporcionan información sobre las interacciones moleculares.
- La hexoquinasa (E.C.2.7.1.1) juega un papel crucial en el metabolismo de la glucosa.
- Comprender la unión enzima-sustrato es clave para el desarrollo de fármacos.
Objetivo del estudio:
- Para investigar los efectos de los isótopos en la unión de la glucosa al cerebro humano hexokinasa.
- Para comparar estos efectos con y sin un análogo beta,gamma-CH(2)-ATP.
- Para aclarar las bases estructurales del reconocimiento enzima-sustrato.
Principales métodos:
- Medición de las constantes de equilibrio para la asociación glucosa-hexokinasa.
- Utilizando la glucosa etiquetada isotópicamente ([1-3H]-, [2-3H]-, [3-3H]-, [4-3H]-, [5-3H]-, [6,6-3H2]-, [2-14C]-, [6-14C]-glucosa).
- Comparación de datos vinculantes en la presencia y ausencia de un análogo de nucleótido.
Principales resultados:
- Se observaron efectos isotópicos significativos en las posiciones de glucosa H1, H5 y H6.
- Efectos isotópicos cuantificados para varias moléculas de glucosa etiquetadas que se unen a la hexokinasa.
- Se detectaron cambios en el equilibrio de unión influenciados por la presencia de nucleótidos.
Conclusiones:
- La unión de nucleótidos induce cambios conformacionales sutiles en la hexokinasa, que afectan a los residuos Asn683 y Glu742.
- Estos cambios influyen en la interacción con grupos hidroxilo específicos de glucosa (OH6).
- Los efectos isotópicos sirven como sondas sensibles para la dinámica del sitio activo de la enzima durante la unión al sustrato.
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