A zymogen (or proenzyme) is an inactive enzyme precursor. A zymogen requires a biochemical change (such as a hydrolysis reaction revealing the active site, or changing the configuration to reveal the active site) for it to become an active enzyme. The biochemical change usually occurs in a lysosome where a specific part of the precursor enzyme is cleaved in order to activate it. The amino acid chain that is released upon activation is called the activation peptide.

[edit] Examples

Examples of zymogens:

• Trypsinogen
• Chymotrypsinogen
• Pepsinogen
• Most proteins in the coagulation system
• Some of the proteins of the complement system
• Caspases
• Proelastase
• Prolipase

[edit] See also

Look up Zymogen in
Wiktionary, the free dictionary.

• Webster entry on zymogen

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