[en-zahym] 
| 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. |
| en·zyme (ěn'zīm) 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. |
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.
enzyme en·zyme (ěn'zīm)
n.
Any of numerous proteins or conjugated proteins produced by living organisms and functioning as specialized catalysts for biochemical reactions.
enzyme (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. |
zaɪm