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Un interruptor molecular y un cable de protones sincronizan los sitios activos en las enzimas de tiamina
René A W Frank1, Christopher M Titman, J Venkatesh Pratap
1Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, UK.
Science (New York, N.Y.)
|October 30, 2004
Resumen
Los cofactores de tiamina difosfato (ThDP) en la piruvato deshidrogenasa E1 se comunican a través de un cable de protones. Este mecanismo sincroniza la actividad enzimática y explica las propiedades cinéticas de las enzimas dependientes de la tiamina.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- La cinética de las enzimas.
- Biología molecular La biología molecular.
Sus antecedentes:
- El difosfato de tiamina (ThDP) es un cofactor crucial para numerosas enzimas metabólicas.
- El componente E1 del complejo de piruvato deshidrogenasa utiliza ThDP en sus sitios activos.
Objetivo del estudio:
- Investigar el mecanismo de comunicación entre los cofactores ThDP en el componente E1.
- Aclarar cómo esta comunicación influye en la catálisis y estructura de las enzimas.
Principales métodos:
- Investigó la comunicación entre los sitios activos de ThDP en la piruvato deshidrogenasa E1.1.
- Se analizó la transferencia de protones a través de un túnel ácido, denominado "cable de protones".
Principales resultados:
- Se demostró la comunicación entre ThDPs a través de 20 angstroms a través de un cable de protones.
- Se demostró que el alambre de protones facilita la catálisis recíproca ácido/base y la conmutación conformacional.
- Sincronización observada de eventos catalíticos y cambios conformacionales.
Conclusiones:
- El mecanismo del "cable de protones" explica la organización oligomérica y la asimetría conformacional de E1.1.
- Esta vía de comunicación explica las propiedades cinéticas de "ping-pong" observadas en E1 y otras enzimas dependientes de la tiamina.
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