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en·zyme 
Audio Help [en-zahym] Pronunciation Key
Audio Help [en-zahym] Pronunciation Key –noun Biochemistry.
| 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. |
| Dictionary.com Unabridged (v 1.1) Based on the Random House Unabridged Dictionary, © Random House, Inc. 2006. |
enzyme
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| © 2008 Encyclopædia Britannica, Inc. |
| en·zyme
Audio Help (ěn'zīm) Pronunciation Key
n. Any of numerous proteins or conjugated proteins produced by living organisms and functioning as biochemical catalysts. [German Enzym, from Medieval Greek enzūmos, leavened : Greek en-, in; see en-2 + Greek zūmē, leaven, yeast.] en'zy·mat'ic (-zə-māt'ĭk), en·zy'mic (-zī'mĭk, -zĭm'ĭk) adj., en'zy·mat'i·cal·ly, en·zy'mi·cal·ly adv. |
| The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2006 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved. |
enzyme
1881, as a biochemical term, from Ger. Enzym, coined 1878 by Ger. physiologist Wilhelm Kühne (1837-1900), from Gk. enzymos "leavened," from en- "in" + zyme "leaven."
| Online Etymology Dictionary, © 2001 Douglas Harper |
| enzyme | |
noun | |
| any of several complex proteins that are produced by cells and act as catalysts in specific biochemical reactions |
| WordNet® 3.0, © 2006 by Princeton University. |
enzyme
Audio Help (ěn'zīm) Pronunciation Key
(click for larger image in new window) 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. |
| The American Heritage® Science Dictionary Copyright © 2002 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved. |
enzyme [(en-zeyem)]
A protein molecule that helps other organic molecules 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.
[Chapter:] Life Sciences
| The American Heritage® New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved. |
Enzyme
En"zyme\, n. [Pref. en- (Gr. ? in) + Gr. ? leaven.] (Physiol. Chem.) An unorganized or unformed ferment, in distinction from an organized or living ferment; a soluble, or chemical, ferment. Ptyalin, pepsin, diastase, and rennet are good examples of enzymes.| Webster's Revised Unabridged Dictionary, © 1996, 1998 MICRA, Inc. |
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