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

Wiele białek ma wiele podjednostek, z których każda zawiera oddzielne miejsce wiązania liganda.
Kiedy cząsteczka, znana jako modulator, wiąże się z jedną z podjednostek, wyzwala zmianę konformacyjną w miejscach wiązania innych podjednostek, zmieniając ich powinowactwo do odpowiednich ligandów. Nazywa się to kooperatywnym przejściem allosterycznym i można je wyjaśnić za pomocą kilku modeli teoretycznych.
Model uzgodniony lub "wszystko albo nic" zakłada, że wszystkie podjednostki istnieją razem w konformacji "wyłączonej" lub "włączonej".
Wiązanie może wystąpić w dowolnej formie, jednak stan "włączony" ma większe powinowactwo do liganda niż stan "wyłączony". Kiedy ligand wiąże się w którejkolwiek z podjednostek, sprzyja jednoczesnej transformacji wszystkich miejsc wiązania do formy o wysokim powinowactwie.
Kooperatywność można również wyjaśnić za pomocą modelu sekwencyjnego, który zakłada, że każda podjednostka może istnieć niezależnie w stanie wysokiego lub niskiego powinowactwa, ale bardziej prawdopodobne jest, że będzie w stanie wysokiego powinowactwa, gdy ligand jest związany z którąkolwiek z podjednostek. 
Miejsca wiązania białek allosterycznych są zwykle mieszanką elastycznych i stałych segmentów łańcucha aminokwasowego. Kiedy ligand się wiąże, te niestabilne części są stabilizowane w określonej konformacji, a to wpływa na kształt miejsc wiązania na innych podjednostkach. 
Hemoglobina jest przykładem białka tetramerycznego, które ulega kooperatywnemu przejściu allosterycznym, gdy wiąże się tlen.
Każda podjednostka hemoglobiny ma pojedyncze miejsce wiązania. Kiedy jedna cząsteczka tlenu wiąże się z pojedynczą podjednostką, kooperatywność zwiększa powinowactwo do tlenu w pozostałych miejscach wiązania, ułatwiając tlenowi wiązanie się z cząsteczką hemoglobiny, która jest już związana z tlenem.

<ol>
	<li>Cornish-Bowden, A. (2014), Zrozumienie interakcji allosterycznych i kooperacyjnych w enzymach. LUTY J, 281: 621-632. doi:10.1111/febs.12469</li>
	<li>Alberts et al., wydanie 6; strony 152-153</li>
	<li>Lehninger Zasady biochemii, wydanie 5, strony 162,165</li>
</ol>

kooperacyjne przejścia allosteryczne

Przejście allosteryczne może zachodzić w białkach multimerycznych, gdzie każda podjednostka białka ma swoje własne miejsce wiązania liganda. Kiedy ligand wiąże się z którąkolwiek z tych podjednostek, wyzwala zmianę allosteryczną, która wpływa na miejsca wiązania w innych podjednostkach; może to zmienić powinowactwo innych miejsc dla ich odpowiednich ligandów. Zdolność białka do zmiany kształtu miejsca wiązania przypisuje się obecności w strukturze mieszanki elastycznych i stabilnych segmentów. Cząsteczka, która wyzwala tę zmianę, nazywana jest modulatorem. Do wyjaśnienia kooperatywności białek multimerycznych często stosuje się dwa modele: model skoncentrowany i model sekwencyjny. Model skoncentrowany, znany również jako model „wszystko albo nic”, zakłada, że wszystkie podjednostki multimerycznego białka przełączają się jednocześnie między konformacją „włączoną” i „wyłączoną”. W formie „włączonej” miejsca wiązania mają wysokie powinowactwo do odpowiednich ligandów, a w formie „wyłączonej” miejsca wiązania mają niskie powinowactwo. Kiedy ligand wiąże się z którąkolwiek z podjednostek, sprzyja konwersji do postaci o wysokim powinowactwie, jednocześnie zmieniając konformację wszystkich innych miejsc wiązania białka. Chociaż ligand może wiązać się z dowolną formą, łatwiej jest mu się związać, gdy jest w formie o wysokim powinowactwie. Model sekwencyjny zakłada, że każda podjednostka multimerycznego białka może istnieć niezależnie w konformacji „włączonej” lub „wyłączonej”, czyli w formie o niskim lub wysokim powinowactwie, niezależnie od stanu pozostałych podjednostek. Wiązanie ligandu z podjednostką zmienia równowagę pomiędzy formami o niskim i wysokim powinowactwie, tak że jest bardziej prawdopodobne, że podjednostka będzie w postaci o wysokim powinowactwie. Dodatkowo wiązanie ligandu z jedną podjednostką przesuwa równowagę pozostałych podjednostek białka. Zwiększa to prawdopodobieństwo, że po związaniu jednego liganda inny ligand zwiąże się z inną podjednostką. Ta kooperatywność zwiększa wrażliwość białka na stężenie ligandu. Wiązanie ligandu w jednym miejscu może zmienić powinowactwo całej cząsteczki białka, umożliwiając w ten sposób szybką reakcję przy niskich stężeniach.

Kooperacyjne przejścia allosteryczne

Kooperacyjne przejścia allosteryczne mogą zachodzić w białkach multimerycznych, w których każda podjednostka białka ma swoje własne miejsce wiązania ligandu. Kiedy ligand ...

Education

JoVE Core

Cell Biology

Biologia komórki

Unit 1

Jednostka 1

Energy and Catalysis

Energia i kataliza

KEY TERMS AND CONCEPTS

Kluczowe terminy i pojęcia

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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the equilibrium binding constant and binding strength

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

How Equilibrium Binding Constant Affects Binding

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Free Energy and Reaction Direction

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Cells Stay Out of Equilibrium

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oxidation-and-reduction-of-organic-molecules

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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...

ribozymes

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atp energy storage and release

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atp and macromolecule synthesis

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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 Cell Biology illustrates complex cellular processes in easy-to-understand yet comprehensive animated video lessons. This collection focuses on the essential components and functions of cells, including organelles and membranes, cellular transport, and cell energetics. It is complemented by scientist-in-action videos that demonstrate the application of cell biology in real-world research experiments.

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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Macromolecules

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lipid-derived-compounds-in-the-human-body

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Construct an explanation to illustrate relationships between structure and function of major macromolecules essential for life.

LS.Bio.1.1

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Turnover Number and Catalytic Efficiency

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Catalytically Perfect Enzymes

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Introduction to Mechanisms of Enzyme Catalysis

For many years, scientists thought that enzyme-substrate binding took place in a simple &#34;lock-and-key&#34; fashion. This model stated that the enzyme ...

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

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The Nucleus

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Endoplasmic Reticulum

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Ribosomes

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Golgi Apparatus

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Lysosomes

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Peroxisomes

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Background
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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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