Zymogen n. : 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.

Example:
What is a Zymogen & phosphorylation cascade, what is the significance of metabolic events affected by a cascad?

Taxonomy
zymogen, enzyme, zymogens, free encyclopedia, active site, activation, proteins, precursor, search, proenzyme, configuration, synthesised, external environment, fungal cell, digestive enzymes, free dictionary, Personal tools, Interaction.

Defination from the web:
zymogen requires a biochemical change (such as a hydrolysis reaction revealing the active site, or changing the configuration to reveal the ... The pancreas secretes zymogens partly to prevent the enzymes from digesting proteins in the cells in which they are synthesised. ...