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

다른 자리 입체성 (알로스테릭) 조절은효소 활성 부위를 제외한 뚜렷한 부위를 통해 효소를 조절하는 것을 칭합니다.효소 활성 부위가 아닌 별개의 부위를 통해 효소를 조절하는 것을 칭합니다.분자가 다른 자리 입체성 부위 같은 곳에 결합할 때분자가 다른 자리 입체성 부위 같은 곳에 결합할 때이 결합은 구조적 변화를 유발하거나효소 안의 모양을 바꿉니다.이 같은 행동은기질을 위한 효소 활성 부위의 친화력을 높일 수 있고이는 효소 활동을 촉진 시킵니다.이 과정은 다른 자리 입체성 활성화라 부릅니다.반응 속도인 기질 농도 그래프에서다른 자리 입체성 활성화는양의 S-모양 곡선으로 표현됩니다.효소가 활성화할 때까지 지체 시간이 있는 곳이죠.그다음, 활성 부위의 급상승으로 인해높은 농도의 기질은 결합 할 수 있고반응 속도를 빠른 속도로 높입니다.반면에, 만약 반응기가 효소에 결합하고구조적 변화를 일으키면이는 기질 결합 친화력을 낮춥니다.이 과정을 알로오스테리 억제라 부릅니다.이 경우에는 효소 기능이 감소하고활성화 상태에서 화학 반응 속도가 느려집니다.활성화 상태에서 화학 반응 속도가 느려집니다.

<ol><li>Cornish-Bowden, A. 효소의 알로스테릭 및 협력 상호 작용 이해. FEBS 저널. 281 (2), 621-6332 (2014).</li><li>Tsai, C.-J., Nussinov, R. 생리학적 및 병리학적 맥락에서 EGFR 활성화의 새로운 알로스테릭 메커니즘. 생물물리학 저널. 117 (1), 5-13 (2019).</li></ol>

다른자리입체성 조절

Allosteric Regulation

효소의 다른자리입체성 조절(allosteric regulation)은 활성부위(active site)와 다른 위치에 분자가 결합하는 것이 효소 활성에 변화를 일으킬 때 발생합니다. 이러한 유형의 조절은 효소의 활동을 증가시키거나 감소시키는 양성 또는 음성일 수 있습니다. 다른자리입체성(allostery)를 보이는 효소의 대부분은 특정 세포 분자의 분해나 합성에 관여하는 물질대사 효소입니다.
 
 다른자리입체성 억제에서, 다른자리입체성 부위에 분자가 결합하면 기질(substrate)에 대한 효소의 친화력(affinity)을 감소시키는 형태 변화를 일으킵니다. 대개 다른자리입체성 억제제는 효소 또는 효소 경로의 산물이며, 효소 생성물이 효소 자신의 생산을 제한하도록 만듭니다. 이는 되먹임억제(feedback inhibition)의 일종으로 과잉 생성을 방지합니다. 전형적인 예는 이소루신(isoleucine; 아이소루신)으로, 이소루신은 자신의 합성에 중요한 효소의 다른자리입체성 억제제입니다.
 
 반대로, 다른자리입체성 활성제는 기질에 대한 효소의 친화력을 증가시키는 형태 변화를 일으킵니다. 다른자리입체성 활성화는 기질 반응 속도를 크게 증가시키며, 이때 S자 곡선으로 대표되는 반응 속도 증가를 보입니다. 예를 들어 세포 외 리간드(ligand)가 막관통 EGF 수용체(transmembrane EGF receptor)에 결합하면 수용체가 형태 변화를 일으켜 세포 내 인산화효소(kinase) 활동을 활성화합니다. 이때 효소가 여러 개의 단위체(subunit)로 구성된 경우, 다른자리입체성 활성제가 단일 단위체에 결합해 모든 관련 단위체에 대한 친화력을 향상하고 모양 변화를 일으킬 수 있습니다.

효소의 알로스테릭 조절은 활성 부위와 다른 부위에 효과기 분자가 결합할 때 발생합니다.

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Biology

생물학

Cellular Processes

세포 과정

Metabolism

신진대사

KEY TERMS AND CONCEPTS

주요 용어 및 개념

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

what is metabolism?

Metabolism, Energy, and Cell Reactions

Metabolism is the set of chemical reactions that happen in a cell. It includes anabolism, which builds molecules, and catabolism, which breaks them down. These reactions help cells manage energy and keep life processes running. Cells use metabolism to turn food into energy, make cell parts, and remove waste products. Food stores potential energy in the bonds between atoms. Catabolic pathways break large food molecules into smaller ones and release that energy. Anabolic pathways use that energy...

first law of thermodynamics

Energy Flow in a Food Web

Energy flow in a food web shows the First Law of Thermodynamics in action. Energy cannot be created or destroyed. It can only change form as it moves through living things and the environment. Sunlight is the starting point. Plants capture radiant energy from the sun during photosynthesis and turn it into chemical energy stored in complex carbohydrates. At the same time, oxygen is released into the atmosphere. Herbivores eat the plants and use those sugars during digestion. The energy is...

second law of thermodynamics

Entropy in Food Web Energy Flow

The Second Law of Thermodynamics explains why entropy increases as energy moves through a system. Entropy means the amount of disorder in a system. Each time energy is transferred or transformed, some energy is lost as unusable heat. That heat can raise the motion of nearby molecules for a short time and make the surroundings less ordered and more random. This idea also appears in a food web. Primary producers, such as plants, take in energy from the sun and make food. During this process,...

kinetic energy

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Kinetic energy is the energy of motion. It appears when an object is moving and can do work or cause change. A waterfall is one clear example. Water behind a dam has potential energy, but when it rushes downward, that moving water has kinetic energy. When the water reaches the bottom and stops moving, its energy can become potential energy again. Kinetic energy also shows up in living systems. Plants absorb light particles, called photons, which move very fast and help create chemical energy...

potential energy

Stored Energy in Motion and Bonds

Stored energy in motion and bonds is called potential energy. It depends on the structure of an object or the position of matter in space. Raising a kettlebell changes its location and increases its potential energy. A stretched rubber band also stores potential energy, which can later change into kinetic energy. Chemical bonds between atoms hold another form of stored energy called chemical energy. These bonds involve attractive forces, and that energy can change into other forms during a...

free energy

Gibbs Free Energy in Chemical Reactions

Gibbs free energy is a measure of useful energy that can be taken from a chemical reaction to do work. It is written as G and named for scientist Gibbs, who discovered it. This energy is what remains after entropy is considered. A reaction can either take in energy or release it. Reactions that absorb energy are called endergonic reactions. Reactions that release energy are called exergonic reactions. The direction of energy flow helps show which type of reaction is happening. Plants carry...

activation energy

How Catalysts Lower Reaction Barriers

Activation energy is the minimum energy a chemical reaction needs to keep going. When the activation energy is higher, the reaction usually happens more slowly. Adding heat can speed the reaction because molecules move faster and collide more often. As reactants collide, bonds break and the reaction moves through an uphill phase. That step creates the transition state, which is an unstable, high-energy state of the reactants. After that, new bonds form, products appear, and free energy is...

hydrolysis of atp

ATP Breakdown and Energy Release

ATP breakdown releases energy for cell work. Adenosine triphosphate, or ATP, can lose one or two phosphate groups when water is added. This hydrolysis reaction is exergonic, which means it releases energy that the cell can use. When one phosphate group is removed, ATP becomes ADP, or adenosine diphosphate. Inorganic phosphate is also released. ADP can then be hydrolyzed again to form AMP, or adenosine monophosphate, after a second phosphate group is removed. ATP has a clear structure. It is...

phosphorylation

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Phosphorylation helps control how proteins work in cells. It is the addition or removal of phosphate groups, and it is the most common chemical change that regulates cellular processes. These changes can alter a protein’s structure, activity, stability, location inside the cell, and interactions with other proteins. During phosphorylation, protein kinases move the terminal phosphate group from ATP to a specific amino acid side chain on a target protein. The amino acids most often...

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How Enzymes Adjust to Their Substrates

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enzyme kinetics

Substrate Effects on Enzyme Rates

Enzyme kinetics examines how enzymes change the rate of a reaction. Enzymes speed reactions by lowering the activation energy of the reactants. The reaction rate is the speed at which an enzyme turns reactants into products, and it can be affected by several factors, including the number of available reactants. Scientists often study enzyme kinetics in a test tube with a fixed amount of enzyme. When more substrate, or reactant, is added, the reaction rate increases because the enzyme can make...

enzyme inhibition

Competitive vs Noncompetitive Inhibitors

Enzyme inhibitors are molecules that reduce enzyme activity by binding to enzymes. Cells use these inhibitors to help regulate normal enzyme function. Drugs and toxins can also block enzymes and change how they work. Some inhibitors bind at the active site, which is the part of the enzyme where the substrate normally fits. Competitive inhibitors do this by occupying the active site and preventing the substrate from binding. If the substrate concentration becomes high enough, it can outcompete...

feedback inhibition

How Cells Control Product Buildup

Cells use enzymes to run biochemical reactions and make the products they need. These reactions are happening constantly, and enzymes speed them up so they happen fast enough to matter. Enzyme activity also has to be regulated. Cells need the right amounts of starting materials, intermediate metabolites, and final products. If these substances build up too much or drop too low, the cell can be harmed. That is why cells use control systems to keep metabolic levels balanced. One important...

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...

cofactors and coenzymes

Enzyme Helpers: Metals, Vitamins, and More

Enzyme helpers are needed for many enzymes to work properly. These helpers fall into two groups: cofactors and coenzymes. Cofactors are metallic ions, while coenzymes are non-protein organic molecules. Both can be tightly bound to an enzyme or attach only when the substrate binds. Cofactors are common in mature proteins, appearing in about 30% of them. They are often added as the enzyme folds and help with catalytic activity. Magnesium is one important cofactor, and it is needed by more than...

key terms and concepts

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

Allosteric Control of Enzyme Speed | JoVE K12

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Allosteric Control of Enzyme Speed

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