Noun
A mother substance, or antecedent, of an enzyme or chemical ferment; -- applied to such substances as, not being themselves actual ferments, may by internal changes give rise to a ferment.
Source: Webster's dictionaryIn order to prevent inappropriate or premature activation of the digestive enzymes (they may, for example, trigger pancreatic self-digestion causing pancreatitis ), these enzymes are secreted as inactive zymogen. Source: Internet
He originally believed those substances to be precursors of antibodies, just as zymogen is a precursor of an enzyme. Source: Internet
In bacteria, a similar strategy of employing an inactive zymogen or prezymogen is used. Source: Internet