Name: how proteins shift shape together
Uploaded: 2023-04-30T18:28:42.000Z
Duration: 1 min 58 s
Channel: JoVE

K12 Standards

north-carolina-k-12-science-standard-course-of-study

North Carolina K-12 Science Standard Course of Study

9-12

Biology

from-molecules-to-organisms-structures-and-processes

From Molecules to Organisms- Structures and Processes

LS.Bio.1.2

Cooperative Allosteric Transitions

Muchas proteínas tienen múltiples subunidades, donde cada subunidad contiene un sitio de unión al ligando separado.
Cuando una molécula, conocida como modulador, se une a una de las subunidades, desencadena un cambio conformacional en los sitios de unión de las otras subunidades, cambiando su afinidad por sus respectivos ligandos. A esto se le llama transición alostérica cooperativa y puede explicarse mediante varios modelos teóricos.
El modelo concertado o "todo o nada" supone que todas las subunidades existen juntas en una conformación "apagada" o "encendida".
La unión puede ocurrir en cualquiera de las formas, sin embargo, el estado "encendido" tiene una mayor afinidad por el ligando que el estado "apagado". Cuando un ligando se une a cualquiera de las subunidades, promueve la transformación simultánea de todos los sitios de unión a la forma de alta afinidad.
La cooperatividad también puede explicarse por el modelo secuencial, que supone que cada subunidad puede existir independientemente en un estado de alta o baja afinidad, pero es más probable que esté en el estado de alta afinidad cuando el ligando está unido a cualquiera de las subunidades. 
Los sitios de unión de las proteínas alostéricas suelen ser una mezcla de segmentos flexibles y fijos de la cadena de aminoácidos. Cuando un ligando se une, estas partes inestables se estabilizan en una conformación particular, y esto afecta la forma de los sitios de unión en las otras subunidades. 
La hemoglobina es un ejemplo de una proteína tetrámera que experimenta una transición alostérica cooperativa cuando el oxígeno se une.
Cada subunidad de la hemoglobina tiene un solo sitio de unión. Cuando una molécula de oxígeno se une a una sola subunidad, la cooperatividad aumenta la afinidad por el oxígeno en los sitios de unión restantes, lo que facilita que el oxígeno se una a una molécula de hemoglobina que ya tiene oxígeno unido a ella.

<ol>
	<li>Cornish‐Bowden, A. (2014), Comprensión de las interacciones alostéricas y cooperativas en las enzimas. FEBS J, 281: 621-632. doi:10.1111/febs.12469</li>
	<li>Alberts et al., 6ª edición; páginas 152-153</li>
	<li>Principios de Bioquímica de Lehninger, 5ª edición, páginas 162,165</li>
</ol>

transiciones alostéricas cooperativas

Pueden ocurrir transiciones alostéricas cooperativas en proteínas multiméricas, donde cada subunidad de la proteína tiene su propio sitio de unión al ligando. Cuando un ligando se une a cualquiera de estas subunidades, desencadena un cambio conformacional que afecta a los sitios de unión en las otras subunidades, esto puede cambiar la afinidad de los otros sitios por sus respectivos ligandos. La capacidad de la proteína para cambiar la forma de su sitio de unión se atribuye a la presencia de una mezcla de segmentos flexibles y estables en la estructura. Una molécula que desencadena este cambio se conoce como modulador.

A menudo se utilizan dos modelos para explicar la cooperatividad en proteínas multiméricas: el modelo concertado y el secuencial. El modelo concertado, también conocido como modelo de todo o nada, plantea la hipótesis de que todas las subunidades de una proteína multimérica cambian simultáneamente entre las conformaciones "encendido" y "apagado". En la forma "activada", los sitios de unión tienen una alta afinidad por sus respectivos ligandos, y en la forma "apagada", los sitios de unión tienen una baja afinidad. Cuando un ligando se une a cualquiera de las subunidades, promueve la conversión a la forma de alta afinidad, cambiando simultáneamente la conformación de todos los demás sitios de unión de la proteína. Aunque un ligando puede unirse a cualquier forma, le resulta más fácil unirse cuando está en la forma de alta afinidad.

El modelo secuencial supone que cada subunidad de una proteína multimérica puede existir independientemente en una conformación "encendida" o "apagada", es decir, en la forma de baja o alta afinidad, independientemente del estado de las otras subunidades. La unión de un ligando a una subunidad cambia el equilibrio entre las formas de baja y alta afinidad, de modo que es más probable que la subunidad esté en la forma de alta afinidad. Además, la unión de un ligando a una subunidad cambia el equilibrio de las otras subunidades de la proteína. Esto aumenta la probabilidad de que una vez que se une un ligando, otro ligando se una a una subunidad diferente. Esta cooperatividad aumenta la sensibilidad de la proteína a la concentración de ligando. La unión de un ligando a un solo sitio puede cambiar la afinidad en toda la molécula de proteína, permitiendo así una respuesta rápida en concentraciones bajas.

Transiciones alostéricas cooperativas

Las transiciones alostéricas cooperativas pueden ocurrir en proteínas multiméricas, donde cada subunidad de la proteína tiene su propio sitio de unión al ligando. Cuando un ligando ...

Education

Educación

JoVE Core

Cell Biology

Biología Celular

Unit 1

Unidad 1

Energy and Catalysis

Energía y Catálisis

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

how proteins shift shape together

Proteins can change shape in a coordinated way during allosteric transitions. In a cooperative transition, one part of the protein affects another part, so the change spreads through the molecule.

These shape changes help proteins switch between different states. The shift can influence how the protein works and how it responds to other molecules.

Cooperative allosteric transitions are an important idea in protein function. They explain how a small change at one site can lead to a larger change across the protein structure.

How Proteins Shift Shape Together

the first law of thermodynamics

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the-equilibrium-binding-constant-and-binding-strength

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oxidation-and-reduction-of-organic-molecules

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introduction-to-mechanisms-of-enzyme-catalysis

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cooperative allosteric transitions

Proteins can change shape in a coordinated way during allosteric transitions. In a cooperative transition, one part of the protein affects another part, so the change spreads through the molecule. These shape changes help proteins switch between different states. The shift can influence how the protein works and how it responds to other molecules. Cooperative allosteric transitions are an important idea in protein function. They explain how a small change at one site can lead to a larger...

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key terms and concepts

Explore cooperative allosteric transitions and how protein shape changes can spread through a molecule to affect protein function in high school biology.

How Proteins Shift Shape Together | JoVE K12

cell biology

JoVE Core Biología Celular ilustra procesos celulares complejos mediante completos vídeos animados fáciles de entender. Esta colección se centra en los componentes esenciales de las células y su funcionamiento, incluyendo los orgánulos y las membranas, el transporte celular y el metabolismo energético celular. Todo este material se complementa con los vídeos de científicos en acción, que muestran la aplicación de la biología celular en experimentos reales de investigación.

Virginia  Standards of Learning

HIgh School

BIO.2

BIO.2.c

Florida Department of Education

High School

Life Science

SC.912.L.18

SC.912.L.18.4

SC.912.L.18.11

Texas Essential Knowledge and Skills

BIO.11

BIO.11.B

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LS.Bio.1.1

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Ligand Binding and Linkage

Ribozymes

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Prokaryotic Cells

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Cytoplasm

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Golgi Apparatus

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LS.Bio.1.3

Analyze how the relationship between structure and function supports life processes within organisms.

How Proteins Shift Shape Together

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