Name: allosteric changes in protein shape
Uploaded: 2023-04-30T18:28:43.000Z
Duration: 1 min 58 s
Channel: JoVE

K12 Standards

Next Generation Science Standards

High School

Life Science

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

From Molecules to Organisms: Structures and Processes

HS-LS1-1

Cooperative Allosteric Transitions

许多蛋白质具有 多个亚基 每个子单元都包含一个 单独的配体结合位点。当一个分子 被称为调制器 绑定到 亚基，它触发 构象变化 在结合位点 其他亚基中 改变他们的亲和力 它们各自的配体。这叫做合作社 变构过渡 可以用 几种理论模型。一致或 全或无模型 假设所有亚基 一起存在于一个关闭中 或经确认。绑定可能发生 任一种形式。但是，开启状态 有更高的亲和力 对于配体 而不是关闭状态。当配体结合在 任何亚基，它促进了 同时转换 所有结合位点 高亲和力形式。合作可以 也可以解释 通过顺序模型，假设每个子单元都可以 独立存在于 高或低亲和力状态 但更有可能是 处于高亲和力状态 当配体结合时 到任何一个亚单位。的结合位点 变构蛋白 通常是 灵活而固定的细分市场 氨基酸链。当配体结合时 这些不稳定的部分 稳定在 特定的构象。这会影响 装订的形状 其他亚基上的位点。血红蛋白是 一种四聚体蛋白 进行合作 变构时 氧结合。血红蛋白的每个亚基 具有单个结合位点。当一分子的氧气 绑定到单个亚基，合作地 增加亲和力 上的氧气 剩下的结合位点 使它更容易 氧气结合 血红蛋白分子 已经绑定了氧气。

<ol>
	<li>Cornish‐Bowden， A. （2014），了解酶中的变构和协同相互作用。FEBS J，281:621-632。doi:10.1111/febs.12469</li>
	<li>Alberts 等人，第 6 版;第 152-153 页</li>
	<li>Lehninger Principles of Biochemistry，第 5 版，第 162,165 页</li>
</ol>

协同变构转变

协同变构转变可以发生在多聚体蛋白质中，其中蛋白质的每个亚基都有其自己的配体结合位点。 当配体与这些亚基中的任何一个结合时，它会引发构象变化，从而影响其他亚基中的结合位点。 这可以改变其他位点对其各自配体的亲和力。 蛋白质改变其结合位点形状的能力归因于结构中灵活和稳定片段的混合存在。 触发这种变化的分子称为调节剂。

通常使用两种模型来解释多聚体蛋白质的协同性：协同模型和顺序模型。 协同模型，也称为全有或全无模型，假设多聚体蛋白质的所有亚基同时在“开”和“关”构象之间切换。 在“开”形式中，结合位点对其各自的配体具有高亲和力，而在“关”形式中，结合位点对其各自的配体具有低亲和力。 当配体与任何一个亚基结合时，它会促进向高亲和力形式的转化，同时改变蛋白质所有其他结合位点的构象。 尽管配体可以结合任何一种形式，但当处于高亲和力形式时更容易结合。

顺序模型假设多聚蛋白的每个亚基可以以“开”或“关”构象独立存在，即以低亲和力或高亲和力形式存在，而不管其他亚基的状态如何。 配体与亚基的结合改变了低亲和力形式和高亲和力形式之间的平衡，使得亚基更有可能处于高亲和力形式。 此外，一个亚基上的配体结合会改变蛋白质中其他亚基的平衡。 这增加了一旦一个配体结合，另一个配体将结合到不同亚基的可能性。 这种协同作用增加了蛋白质对配体浓度的敏感性。 配体在单个位点的结合可以改变整个蛋白质分子的亲和力，从而能够在低浓度下快速响应。

协同变构转变可发生在多聚体蛋白中，其中蛋白的每个亚基都有其自身的配体结合位点。当配体结合时……

Education

教育

JoVE Core

Cell Biology

细胞生物学

Unit 1

第一单元

Protein Function

蛋白质功能

KEY TERMS AND CONCEPTS

关键术语与概念

协作变构转换

allosteric changes in protein shape

Allosteric changes in protein shape help explain how some proteins switch between active and inactive states. These transitions are cooperative, which means a change in one part of the protein can affect other parts of the same molecule.

The video focuses on how these shifts in shape support protein function. It also shows that allosteric transitions can be described with different models. In the concerted model, the protein changes shape as a whole. In the sequential model, the change happens step by step across the protein.

These models help students understand how proteins respond to signals in the cell. They also show why protein shape is closely linked to biological activity.

Allosteric Changes in Protein Shape

ligand binding sites

Ligand Binding Sites in Proteins

Ligand binding sites are specific parts of a protein where a ligand can attach. A ligand is a molecule that binds to another molecule, often to help start or change a biological process. These sites matter because the shape and chemistry of the protein help determine which ligands can fit and bind. Proteins do not bind every ligand in the same way. The binding site provides a matching surface that supports a close interaction. In many cases, this interaction is important for how cells respond...

protein-protein interfaces

Protein Binding Surfaces and Contacts

Protein binding surfaces and contacts help proteins recognize and attach to each other. These interfaces are the regions where two proteins meet and interact. They are important for many cell processes and for how proteins work together. A protein-protein interface is not just a random touch point. It is shaped by the three-dimensional form of each protein. The matching surfaces allow a stable interaction to form when the proteins fit together well. Studying these interfaces helps explain how...

conserved binding sites

Conserved Binding Sites in Protein Families

Conserved binding sites are regions on proteins that stay similar across related proteins. These shared areas often help proteins interact with the same molecules. For this reason, they are useful clues when comparing protein families. A conserved site can help identify where a protein binds. It can also show which parts of the protein are important for function. When the same pattern appears in several proteins, it suggests that the site has been kept through evolution. Scientists look at...

cofactors and coenzymes

Enzyme Helpers: Metals and Vitamins

Enzyme helpers include cofactors and coenzymes. Enzymes are proteins made of amino acids, and the functional groups on those amino acids can drive many chemical reactions through ionic interactions or acid-base reactions. But amino acids alone cannot handle oxidation-reduction and group transfer reactions, so they need non-protein helpers called cofactors. Cofactors are often described as the chemical teeth of an enzyme. They can be metal ions or organic molecules called coenzymes. These...

cooperative allosteric transitions

Allosteric changes in protein shape help explain how some proteins switch between active and inactive states. These transitions are cooperative, which means a change in one part of the protein can affect other parts of the same molecule. The video focuses on how these shifts in shape support protein function. It also shows that allosteric transitions can be described with different models. In the concerted model, the protein changes shape as a whole. In the sequential model, the change happens...

protein kinases and phosphatases

Protein Kinases and Phosphatases in Cell Control

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gtpases and their regulation

GTPase Molecular Switches and Control

GTPases are molecular switches that help control cell activity. They bind guanosine triphosphate, or GTP, and can change between active and inactive states. This switch-like behavior makes them important in many cell processes. The protein is active when GTP is bound and inactive when guanosine diphosphate, or GDP, is bound. GTPases can also turn themselves off by breaking down GTP into GDP. This built-in control helps cells regulate when the protein is on or off. Their activity is regulated...

covalently linked protein regulators

Protein Regulation by Covalent Bonds

Protein regulation by covalent bonds helps control how cells respond to changing conditions. A covalent bond is a strong chemical link, and in this context it can change how a protein behaves. Some regulators work by attaching a chemical group directly to a protein. This covalent change can alter the protein's activity, its location in the cell, or how long it stays active. Because the change is built into the protein itself, it can have a strong effect on cell function. Covalently linked...

protein complexes with interchangeable parts

protein-complexes-with-interchangeable-parts

Modular Protein Complexes in Cells

Protein complexes in cells can be built from interchangeable parts. This modular design lets some complexes share common subunits while still changing their behavior. A well-known example is the ubiquitin ligase complex called SCF. SCF stands for Skp1-Cullin-F-box, and it helps attach ubiquitin, a small protein tag, to target proteins. The core of SCF stays the same, but the F-box protein can change. The interchangeable F-box subunit gives the complex its specificity. Different F-box proteins...

mechanical protein function

Proteins That Generate Cell Movement

Mechanical proteins help cells and tissues move. They turn chemical energy into force and motion. This process is important in many biological systems. These proteins are also called motor proteins. They interact with cell structures and can produce directed movement. In muscle cells, they support contraction. In other cells, they help with transport and shape changes. Mechanical protein function is a key part of how living systems work. It links protein activity to movement at the cellular...

structural protein function

Structural Proteins in Cells and Tissues

Structural proteins help cells and tissues keep their shape and strength. They are an important part of living systems because they provide support where it is needed most. Many structural proteins form fibers or other sturdy forms that resist stretching and wear. These proteins work as building materials in the body and help keep structures stable over time. Examples of structural proteins include collagen, actin, myosin, and keratin. Each one supports a different part of the body, but all...

protein networks

Mapping Protein Interaction Networks

Protein interaction networks show how proteins work together inside a cell. These networks help scientists see which proteins connect with each other and how those links support cell activity. Researchers often use online tools to build and study these networks. The transcript points to IntAct and STRING as examples of resources that can help predict and organize protein interactions. These tools make it easier to compare protein links and look for patterns in the network. Protein networks...

key terms and concepts

Explore cooperative allosteric transitions and learn how protein shape changes can switch proteins between active and inactive states using concerted and sequential models.

Allosteric Changes in Protein Shape | JoVE K12

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HS-LS1-2

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HS-LS1-3

Allosteric Changes in Protein Shape

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