Name: how enzymes adjust to their substrates
Uploaded: 2019-03-11T09:21:10.000Z
Duration: 1 min 13 s
Channel: JoVE

Ферменты, обычно являющиеся белками, работают с помощью привязки к субстрату, молекуле, на которую они действуют, и для которой они специфичны. Это означает, что они могут привязаться только к определённым субстратам. В основном это свойство определяется формой и химическими характеристиками их активного сайта, области фермента которая привязывается к субстрату.В соответствии с моделью индуцированной посадки, описывающей деятельность фермента, эта привязка изменяет подтверждение, форму, обоих, фермента и субстрата. Это подводит субстрат ближе к переходному состоянию с более высокой энергией, необходимому для реакции. Например, ослабляя свои связи, так что он может быстрее реагировать.После того, как продукт реакции получен, выпускается фермент, который может использоваться как катализатор реакции еще раз.

Теория Кошланда (модель "индуцированного соответствия")

Induced-fit Model

Большинство химических реакций в клетках требуют ферментов-биологических катализаторов, которые ускоряют реакцию без использования или постоянно меняются. Они работают за счет уменьшения энергии активации, необходимой для того, чтобы реагенты преобразовывались в продукты. Ферменты, которые обычно являются белками, работают путем связывания с субстратом – молекулой реакции, на которую они действуют.

<h4>Специфика</h4>

Ферменты обладают субстратной специфичностью, а это означает, что они могут связываться только с определенными субстратами. Это в основном определяется формой и химическими характеристиками их активного участка – области фермента, который связывается с субстратом.

Согласно индуцированной модели активности ферментов, это связывание изменяет конформацию или форму как фермента, так и субстрата. Это приближает субстрат к более высокому энергетическому переходному государству, необходимому для реакции, например, путем ослабления связей, с тем чтобы он можно было с большей готовностью реагировать. Ферменты могут также ускорить реакцию, создавая условия в активном месте, которые являются более благоприятными для реакции, чтобы продолжить, чем окружающая клеточная среда.

Как только продукты реакции формируются, они высвобождаются из активного участка и фермент может быть использован для катализы реакций еще раз.

Для большинства химических реакций в клетках требуются ферменты — биологические катализаторы, которые ускоряют реакцию, не потребляясь и не изменяясь навсегда. Они...

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Biology

Биология

Cellular Processes

Клеточные процессы

Metabolism

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KEY TERMS AND CONCEPTS

ОСНОВНЫЕ ТЕРМИНЫ И ПОНЯТИЯ

how enzymes adjust to their substrates

Enzymes speed up many chemical reactions in cells. They are biological catalysts, so they increase reaction speed without being consumed or permanently changed. They do this by lowering the activation energy needed to turn reactants into products.

Enzymes are proteins that usually work by binding to a substrate, which is the reactant molecule they act on. They show substrate specificity, meaning they bind only certain substrates. This specificity depends mainly on the shape and chemical features of the enzyme’s active site, the region that binds the substrate.

The induced-fit model explains what happens after the substrate binds. The binding changes the enzyme’s shape, or conformation. This change helps bring the substrate closer to the higher-energy transition state needed for the reaction, such as by weakening bonds so the substrate can react more easily.

Enzymes can also make the active site a better place for the reaction than the surrounding cell environment. After the products form, they leave the active site. The enzyme can then catalyze the reaction again.

How Enzymes Adjust to Their Substrates

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Metabolism, Energy, and Cell Reactions

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first law of thermodynamics

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activation energy

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induced-fit model

Enzymes speed up many chemical reactions in cells. They are biological catalysts, so they increase reaction speed without being consumed or permanently changed. They do this by lowering the activation energy needed to turn reactants into products. Enzymes are proteins that usually work by binding to a substrate, which is the reactant molecule they act on. They show substrate specificity, meaning they bind only certain substrates. This specificity depends mainly on the shape and chemical...

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...

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Competitive vs Noncompetitive Inhibitors

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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 enzyme active sites change shape in the induced-fit model, helping substrates reach the transition state and reactions happen faster.

How Enzymes Adjust to Their Substrates | JoVE K12

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How Enzymes Adjust to Their Substrates

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