enzyme

American  

[en-zahym] / ˈɛn zaɪm /

noun

Biochemistry.

1. any of various proteins, as pepsin, originating from living cells and capable of producing certain chemical changes in organic substances by catalytic action, as in digestion.

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enzyme British  

/ ɛnˈzaɪmɪk, ˈɛnzaɪm, ˌɛnzaɪˈmætɪk, -zɪ-, -ˈzɪm- /

noun

1. any of a group of complex proteins or conjugated proteins that are produced by living cells and act as catalysts in specific biochemical reactions

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enzyme Scientific  

/ ĕn′zīm /

1. Any of numerous proteins produced in living cells that accelerate or catalyze the metabolic processes of an organism. Enzymes are usually very selective in the molecules that they act upon, called substrates, often reacting with only a single substrate. The substrate binds to the enzyme at a location called the active site just before the reaction catalyzed by the enzyme takes place. Enzymes can speed up chemical reactions by up to a millionfold, but only function within a narrow temperature and pH range, outside of which they can lose their structure and become denatured. Enzymes are involved in such processes as the breaking down of the large protein, starch, and fat molecules in food into smaller molecules during digestion, the joining together of nucleotides into strands of DNA, and the addition of a phosphate group to ADP to form ATP. The names of enzymes usually end in the suffix –ase.

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enzyme Cultural  

1. A protein molecule that helps other organic molecules (see also organic molecule) enter into chemical reactions with one another but is itself unaffected by these reactions. In other words, enzymes act as catalysts for organic biochemical reactions.

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Other Word Forms

Derived Forms

• enzymatic
  adjective

Etymology

Origin of enzyme

First recorded in 1880–85; from Medieval Greek énzymos “leavened,” from Greek en- en- ² + zȳ́m(ē) “leaven” + -os, adjective suffix

Explanation

An important element in human chemistry, an enzyme is a protein manufactured by a cell, and is a catalyst in various biological functions. For example, enzymes help break down larger molecules of starch, fat, and protein during digestion. The word enzyme was coined by a German physiologist in the late 1800s to name a digestive process that scientists had been observing. The word was later given to the actual agents discovered to spark the reactions, taken from the Greek énzymos, which meant "leavened." (Leavening makes bread rise.) Remember that the word enzyme is spelled with a y and not an i, which makes sense, since when scientists observe chemical processes, they often ask "why?"

Example Sentences

Similar treatments for the enzyme deficiencies known as Sanfilippo, Pompe and Gaucher diseases are in early clinical trials, or soon will be.

From Barron's • Jun. 3, 2026

Food and Drug Administration approved Avlayah, which taps the transferrin receptor to bring in the enzyme that is missing from the brain cells of children born with Hunter Syndrome.

From Barron's • Jun. 3, 2026

ION224 blocks an enzyme known as DGAT2, which helps the liver produce and store fat.

From Science Daily • May 27, 2026

Known as hormone-sensitive lipase, or HSL, the enzyme was thought to work mainly as the body's emergency fuel switch, helping release stored fat when energy runs low.

From Science Daily • May 8, 2026

“Rahajamati. His article attacks Tanida’s theory of enzyme fusion—the concept of changing the chemical structure of the enzyme blocking the step in the metabolic pathway.”

From "Flowers for Algernon" by Daniel Keyes

Related Words

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• motivation
• stimulant