Enzyme

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A multi-panel diagram illustrates how a substrate binds to an enzyme's active site through induced fit, leading to product formation, and shows how non-substrates and allosteric regulators can alter enzyme activity by binding to different sites on the enzyme.

We Couldn't Live Without Enzymes

A person in a white coat pours rennet from a measuring tube into a large copper vat of milk while stirring, part of the cheese making process.

Diagram illustrating the lock-and-key model of enzyme action, showing a substrate fitting precisely into the enzyme's active site, while non-substrate shapes do not fit. The enzyme is depicted with a complex outline and labeled binding site, emphasizing specificity.

Diagram showing how enzymes catalyze reactions: enzymes bind to substrates, form intermediate complexes, and release products. The lower section details specific mechanisms for acetylcholinesterase, sucrose phosphorylase, and maltose phosphorylase, with labeled steps and components.

Two graphs illustrating enzyme action: the left graph shows a Michaelis-Menten curve with reaction velocity rising and leveling off as substrate concentration increases; the right graph compares cooperative curves, with positive cooperativity showing a steep rise, negative cooperativity a gradual rise, and both labeled accordingly.

The chemistry of digestion: How food is broken down

What happens to your body after you die?

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Enzyme: Media

biochemistry

Videos

We Couldn't Live Without Enzymes

We Couldn't Live Without Enzymes

Enzymes are a type of catalyst, which are substances that speed up a chemical reaction.

Video: Encyclopædia Britannica, Inc.

The chemistry of digestion: How food is broken down

The chemistry of digestion: How food is broken down

Learn about the chemical process the human body uses to digest carbohydrates, proteins,...

Video: © American Chemical Society (A Britannica Publishing Partner)

What happens to your body after you die?

What happens to your body after you die?

Learn what happens to the body after death.

Video: © American Chemical Society (A Britannica Publishing Partner)

Images

A multi-panel diagram illustrates how a substrate binds to an enzyme's active site through induced fit, leading to product formation, and shows how non-substrates and allosteric regulators can alter enzyme activity by binding to different sites on the enzyme.

enzyme-substrate binding

In the induced-fit theory of enzyme-substrate binding, a substrate approaches the...

Encyclopædia Britannica, Inc.

A person in a white coat pours rennet from a measuring tube into a large copper vat of milk while stirring, part of the cheese making process.

rennet in cheese making

Rennet, which contains the protease enzyme chymosin, being added to milk during cheese...

© Fedecandoniphoto/Dreamstime.com

Diagram illustrating the lock-and-key model of enzyme action, showing a substrate fitting precisely into the enzyme's active site, while non-substrate shapes do not fit. The enzyme is depicted with a complex outline and labeled binding site, emphasizing specificity.

enzyme; active site

The active site of an enzyme is a groove or pocket that binds a specific substrate.

Encyclopædia Britannica, Inc.

Diagram showing how enzymes catalyze reactions: enzymes bind to substrates, form intermediate complexes, and release products. The lower section details specific mechanisms for acetylcholinesterase, sucrose phosphorylase, and maltose phosphorylase, with labeled steps and components.

The actions of enzymes

Mechanisms of enzymatic action.

Encyclopædia Britannica, Inc.

Two graphs illustrating enzyme action: the left graph shows a Michaelis-Menten curve with reaction velocity rising and leveling off as substrate concentration increases; the right graph compares cooperative curves, with positive cooperativity showing a steep rise, negative cooperativity a gradual rise, and both labeled accordingly.

enzyme reaction curve; Michaelis-Menten kinetics

According to Michaelis-Menten kinetics, if the velocity of an enzymatic reaction...

Encyclopædia Britannica, Inc.

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