View source for Zymogen

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==Overview==
A '''zymogen''' (or '''proenzyme''') is an inactive [[enzyme]] [[Protein precursor|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.

==Etymology==
Very often the suffix "-ogen" can be added to the name of the enzyme to indicate that it is in the precursor form. Some enzymes have a pro- prefix to denote their inactive status e.g. Proalbumin, which is converted into albumin. [http://en.wiktionary.org/wiki/Webster_1913:1681#zyme] 

==Examples==
Examples of zymogens:

* [[Trypsinogen]]
* [[Chymotrypsinogen]]
* [[Pepsinogen]]
* Most proteins in the [[coagulation|coagulation system]]
* Some of the proteins of the [[Complement_(biology)|complement system]]
* [[Caspase|Caspases]]
* [[Proelastase]]
* [[Prolipase]]

==See also==
* [http://webster.com/cgi-bin/dictionary?book=Dictionary&va=zymogen Webster entry on zymogen]
* [http://en.wiktionary.org/wiki/Webster_1913:1681#zyme Wiktionary entry on zyme/zymogen]

[[Category:Enzymes]]


[[cs:Zymogen]]
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[[he:זימוגן]]
[[pl:Proenzym]]
[[pt:Zimógeno]]
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