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

Viele Proteine haben mehrere Untereinheiten, wobei jede Untereinheit eine separate Ligandenbindungsstelle enthält.
Wenn ein Molekül, ein sogenannter Modulator, an eine der Untereinheiten bindet, löst es eine Konformationsänderung in den Bindungsstellen der anderen Untereinheiten aus, wodurch sich ihre Affinität zu ihren jeweiligen Liganden ändert. Dies wird als kooperativer allosterischer Übergang bezeichnet und kann durch verschiedene theoretische Modelle erklärt werden.
Das konzertierte oder "Alles-oder-Nichts"-Modell geht davon aus, dass alle Untereinheiten zusammen in einer "aus"- oder "ein"-Konformation existieren.
Die Bindung kann in beiden Formen erfolgen, jedoch hat der "Ein"-Zustand eine höhere Affinität für den Liganden als der "Aus"-Zustand. Wenn ein Ligand an eine der Untereinheiten bindet, fördert er die gleichzeitige Umwandlung aller Bindungsstellen in die hochaffine Form.
Die Kooperativität kann auch durch das sequentielle Modell erklärt werden, das davon ausgeht, dass jede Untereinheit unabhängig voneinander in einem Zustand mit hoher oder niedriger Affinität existieren kann, sich aber eher im Zustand mit hoher Affinität befindet, wenn der Ligand an eine der Untereinheiten gebunden ist. 
Die Bindungsstellen allosterischer Proteine sind in der Regel eine Mischung aus flexiblen und festen Segmenten der Aminosäurekette. Wenn ein Ligand bindet, werden diese instabilen Teile in einer bestimmten Konformation stabilisiert, was sich auf die Form der Bindungsstellen an den anderen Untereinheiten auswirkt. 
Hämoglobin ist ein Beispiel für ein tetrameres Protein, das einen kooperativen allosterischen Übergang durchläuft, wenn Sauerstoff bindet.
Jede Untereinheit des Hämoglobins hat eine einzige Bindungsstelle. Wenn ein Sauerstoffmolekül an eine einzelne Untereinheit bindet, erhöht die Kooperativität die Affinität zu Sauerstoff an den verbleibenden Bindungsstellen, wodurch es für Sauerstoff einfacher wird, an ein Hämoglobinmolekül zu binden, an das bereits Sauerstoff gebunden ist.

<ol>
	<li>Cornish-Bowden, A. (2014), Allosterische und kooperative Wechselwirkungen in Enzymen verstehen. FEBS J, 281: 621-632. doi:10.1111/febs.12469</li>
	<li>Alberts et al., 6. Auflage; Seiten 152-153</li>
	<li>Lehninger Prinzipien der Biochemie, 5. Auflage, Seiten 162,165</li>
</ol>

kooperative allosterische Übergänge

Kooperative allosterische Übergänge können bei multimeren Proteinen auftreten, bei denen jede Untereinheit des Proteins ihre eigene Liganden-Bindungsstelle hat. Wenn ein Ligand an eine dieser Untereinheiten bindet, löst dies eine Konformationsänderung aus, die die Bindungsstellen in den anderen Untereinheiten beeinflusst; dies kann die Affinität der anderen Stellen für ihre jeweiligen Liganden verändern. Die Fähigkeit des Proteins, die Form seiner Bindungsstelle zu ändern, wird der Anwesenheit einer Mischung aus flexiblen und stabilen Segmenten in der Struktur zugeschrieben. Ein Molekül, das diese Änderung auslöst, wird als Modulator bezeichnet.

Zwei Modelle werden oft verwendet, um die Kooperativität in multimeren Proteinen zu erklären: das konzertierte Modell und das sequenzielle Modell. Das konzertierte Modell, auch bekannt als Alles-oder-Nichts-Modell, geht davon aus, dass alle Untereinheiten eines multimeren Proteins gleichzeitig zwischen den „On“- und „Off“-Konformationen wechseln. In der „On“-Form haben die Bindungsstellen eine hohe Affinität zu ihren jeweiligen Liganden, und in der „Off“-Form haben die Bindungsstellen eine niedrige Affinität. Wenn ein Ligand an eine der Untereinheiten bindet, fördert dies den Übergang zur Form mit hoher Affinität und ändert gleichzeitig die Konformation aller anderen Bindungsstellen des Proteins. Obwohl ein Ligand an beide Formen binden kann, ist es einfacher, wenn er in der Form mit hoher Affinität vorliegt.

Das sequenzielle Modell nimmt an, dass jede Untereinheit eines multimeren Proteins unabhängig voneinander in einer „On“- oder „Off“-Konformation existieren kann, das heißt in entweder der Form mit niedriger oder hoher Affinität, unabhängig vom Zustand der anderen Untereinheiten. Die Bindung eines Liganden an eine Untereinheit verändert das Gleichgewicht zwischen den Formen mit niedriger und hoher Affinität, sodass es wahrscheinlicher wird, dass die Untereinheit in der Form mit hoher Affinität vorliegt. Zusätzlich verschiebt die Bindung eines Liganden an eine Untereinheit das Gleichgewicht für die anderen Untereinheiten im Protein. Dies erhöht die Wahrscheinlichkeit, dass, sobald ein Ligand gebunden ist, ein weiterer Ligand an eine andere Untereinheit bindet. Diese Kooperativität erhöht die Empfindlichkeit des Proteins gegenüber der Ligandenkonzentration. Die Bindung eines Liganden an eine einzelne Stelle kann die Affinität des gesamten Proteinmoleküls ändern und so eine schnelle Reaktion bei niedrigen Konzentrationen ermöglichen.

Kooperative allosterische Übergänge

Kooperative allosterische Übergänge können in multimeren Proteinen auftreten, bei denen jede Untereinheit des Proteins ihre eigene Ligandenbindungsstelle hat. Wenn ein Ligand ...

Education

Lehre

JoVE Core

Cell Biology

Zellbiologie

Unit 1

Einheit 1

Energy and Catalysis

Energie und Katalyse

KEY TERMS AND CONCEPTS

KERNBEGRIFFE UND KONZEPTE

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

Energy Changes in Cells and Matter

The first law of thermodynamics describes how energy changes form in the universe. The total amount of energy stays constant. Energy can move from one place to another or change into a different form, but it cannot be created or destroyed. These energy changes happen in everyday life. A light bulb changes electrical energy into light energy. A gas stove changes chemical energy in natural gas into heat energy. Plants also carry out a major energy transformation when they convert sunlight energy...

the second law of thermodynamics

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endergonic-and-exergonic-reactions-in-the-cell

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the equilibrium binding constant and binding strength

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

How Equilibrium Binding Constant Affects Binding

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non-equilibrium in the cell

Cells Stay Out of Equilibrium

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oxidation and reduction of organic molecules

oxidation-and-reduction-of-organic-molecules

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introduction to mechanisms of enzyme catalysis

introduction-to-mechanisms-of-enzyme-catalysis

How Enzymes Change Shape to Catalyze

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ligand binding and linkage

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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 Zellbiologie veranschaulicht komplexe zelluläre Prozesse in leicht verständlichen und dennoch umfassenden animierten Videolektionen. Diese Sammlung konzentriert sich auf die wesentlichen Bestandteile und Funktionen von Zellen, einschließlich Organellen und Membranen, Zelltransport und Zellenergie. Ergänzt wird sie durch Videos von Wissenschaftlern in Aktion, die die Anwendung der Zellbiologie in realen Forschungsexperimenten demonstrieren.

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

Carry out investigations to illustrate how enzymes act as catalysts for biochemical reactions and how environmental factors affect enzyme activity.

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Prokaryotic Cells

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Cytoplasm

The cytoplasm consists of organelles and a framework of protein scaffolds called the cytoskeleton suspended in an aqueous solution, the cytosol. The ...

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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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