[1] : The Collaborative International Dictionary of English v.0.48

proenzyme \pro"enzyme\, n. . bioch.
   any one of a class of proteins that are converted, in the
   normal course of cellular metabolism, into one or more active
   enzymes; also called zymogen. the conversion usually is due
   to a specific cleavage of a peptide bond by another enzyme,
   or may be due to acid.
   pjc
see also:
zymogen 

[2] : The Collaborative International Dictionary of English v.0.48

zymogen \zym"ogen\, n. zyme + -gen. physiol. chem.
   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.
   1913 webster

         the pancreas contains but little ready-made ferment,
         though there is present in it a body, zymogen, which
         gives birth to the ferment.              --foster.
   1913 webster

[3] : WordNet (r) 2.0

zymogen
     n : any of a group of compounds that are inactive precursors of
         enzymes and require some change such as the hydrolysis
         of a fragment that masks an active enzyme to become
         active syn: proenzyme
see also:
proenzyme 

Zymogen >> Z Words
Zymogen, definition of term: Zymogen
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