Name: allosteric control of enzyme speed
Uploaded: 2025-10-23T11:48:33.000Z
Duration: 1 min 8 s
Channel: JoVE

- La regulación alostérica
se refiere a la regulación

de una enzima en un sitio distinto

al sitio activo de tal enzima.

Cuando una molécula se une a tal sitio,

llamado un sitio alostérico,

la unión puede provocar
un cambio de conformación,

o sea un cambio de la forma de la enzima.

Tal proceso puede aumentar la afinidad

de los sitios activos de la
enzima por sus sustratos,

aumentando la actividad de la enzima.

Este proceso es conocido
como activación alostérica.

En un gráfico de

ritmo de reacción y
concentración de sustrato,

la activación alostérica
puede ser representada

como una curva positiva en forma de S.

Hay una demora hasta
que se active la enzima.

Luego, debido al aumento
repentino de sitios activos,

una gran concentración
de sustrato puede unirse

y acelerar rápidamente la reacción.

Pero, si el efector se une a la enzima,

provocando un cambio de conformación

que disminuye la afinidad
de la unión de sustratos,

tal proceso se llama
inhibición alostérica.

En este caso se disminuye
la función de la enzima

y el ritmo de reacción química

del estado activado.

<ol><li>Cornish‐Bowden, A. Comprensión de las interacciones alostéricas y cooperativas en enzimas. Revista FABS. 281 (2), 621-6332 (2014).</li><li>Tsai, C.-J., Nussinov, R. Mecanismo alostérico emergente de la activación de EGFR en contextos fisiológicos y patológicos. Revista Biofísica. 117 (1), 5-13 (2019).</li></ol>

regulación alostérica

Allosteric Regulation

La regulación alostérica de las enzimas ocurre cuando la unión de una molécula efectora a un sitio diferente al sitio activo provoca un cambio en la actividad enzimática. Este sitio alternativo se llama sitio alostérico y una enzima puede contener más de uno de estos sitios. La regulación alostérica puede ser positiva o negativa, lo que resulta en un aumento o disminución de la actividad enzimática. La mayoría de las enzimas que muestran regulación alostérica son enzimas metabólicas involucradas en la degradación o síntesis de moléculas celulares específicas. Inhibición alostérica En la inhibición alostérica, la unión de una molécula efectora al sitio alostérico provoca un cambio conformacional que reduce la afinidad de la enzima por el sustrato. Con frecuencia, el inhibidor alostérico es un producto de la enzima o de la vía enzimática, lo que permite que los productos enzimáticos limiten su propia producción. Este tipo de inhibición de la retroalimentación evita la sobreproducción de productos. Como ejemplo clásico, la isoleucina es un inhibidor alostérico de una enzima importante en su propia síntesis. Activación alostérica Por el contrario, un activador alostérico provoca un cambio conformacional que aumenta la afinidad de la enzima por su sustrato. La activación alostérica aumenta drásticamente la velocidad de reacción, como lo representa la curva hiperbólica en un gráfico de velocidad de reacción versus concentración de sustrato. Por ejemplo, la unión del ligando extracelular al receptor transmembrana de EGF provoca un cambio conformacional que da como resultado un aumento de la actividad quinasa intracelular del receptor. Si una enzima está compuesta por múltiples subunidades, la unión de un activador alostérico a una sola subunidad puede causar un aumento en la afinidad y un cambio de forma para todas las subunidades afiliadas.

Lectura sugerida

Regulación alostérica

La regulación alostérica de las enzimas ocurre cuando la unión de una molécula efectora a un sitio que es diferente del sitio activo causa un cambio en el ...

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KEY TERMS AND CONCEPTS

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allosteric control of enzyme speed

Allosteric control changes enzyme speed when a molecule binds to a site other than the active site. That alternate binding spot is called an allosteric site. An enzyme can have more than one allosteric site. This type of control can raise or lower enzyme activity.

Many enzymes with allosteric control are metabolic enzymes. They help with the breakdown or the building of specific molecules in cells. In allosteric inhibition, the effector molecule causes a shape change that lowers the enzyme's ability to bind its substrate. Often, the inhibitor is a product of the enzyme or pathway, so the product helps stop more of itself from being made. This feedback inhibition prevents overproduction.

A classic example is isoleucine, which acts as an allosteric inhibitor of an enzyme needed for its own synthesis. Allosteric activation works in the opposite way. An activator changes the enzyme shape so it binds its substrate more strongly. This can greatly increase reaction rate, and it is shown by a hyperbolic curve on a graph of reaction rate versus substrate concentration.

A well-known example of allosteric activation is the EGF receptor. When an extracellular ligand binds to this transmembrane receptor, it changes shape and increases the receptor's intracellular kinase activity. In enzymes with multiple subunits, binding of one activator to a single subunit can also increase the affinity and shape of the other linked subunits.

Allosteric Control of Enzyme Speed

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allosteric regulation

Allosteric control changes enzyme speed when a molecule binds to a site other than the active site. That alternate binding spot is called an allosteric site. An enzyme can have more than one allosteric site. This type of control can raise or lower enzyme activity. Many enzymes with allosteric control are metabolic enzymes. They help with the breakdown or the building of specific molecules in cells. In allosteric inhibition, the effector molecule causes a shape change that lowers the enzyme's...

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key terms and concepts

Learn how allosteric activators and inhibitors change enzyme shape, affect reaction rate, and control feedback in metabolic pathways.

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Allosteric Control of Enzyme Speed

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