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

The interaction of an enzyme with its substrate is highly specific, which means that the enzyme can only bind certain substrates.
This specificity is determined by the shape and chemical characteristics of the active site&#8212; the region of the enzyme that binds to the substrate.
&#160;Induced fit is a widely accepted model to explain enzyme specificity and catalysis. Unlike the lock-and-key model, which hypothesizes that the substrate fits into the enzyme&#39;s active site, the induced-fit model proposes that the enzyme undergoes a change in its three-dimensional shape upon substrate binding.
This conformational change alters the relative positions of specific amino acids of the enzyme to increase their interactions with the substrate. The enzyme-substrate interaction lowers the activation energy for the reaction, increasing the reaction rate.
After the product of the reaction is formed and released from the active site, the enzyme reverts to its original shape and can catalyze additional rounds of the reaction.

induced-fit model

Induced-fit Model

Most chemical reactions in cells require enzymes&#8212;biological catalysts that speed up the reaction without being consumed or permanently changed. They reduce the activation energy needed to convert the reactants into products. Enzymes are proteins, that usually work by binding to a substrate&#8212;a reactant molecule that they act upon.
Enzymes exhibit substrate specificity, meaning that they can only bind to certain substrates. This is mainly determined by the shape and chemical characteristics of their active site&#8212;the region of the enzyme that binds to the substrate.
According to the induced-fit model of enzyme activity, this binding changes the conformation&#8212;or shape&#8212;of the enzyme. This brings the substrate closer to the higher energy transition state needed for the reaction to occur, for instance, by weakening its bonds so that it can more readily react. Enzymes may also speed up a reaction by creating conditions within the active site that are more conducive for the reaction to occur than the surrounding cellular environment.
Once the products of the reaction are formed, they are released from the active site of the enzyme, and the enzyme can catalyze reactions once again.

Most chemical reactions in cells require enzymes&#8212;biological catalysts that speed up the reaction without being consumed or permanently changed. They ...

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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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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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