Chymotrypsinogen: Difference between revisions

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Chymotrypsinogen is a precursor (zymogen) of the digestive enzyme chymotrypsin. It is a single polypetide chain consisting of 245 amino acid residues. It is synthesized in the acinar cells of the pancreas and stored inside membrane-bounded granules at the apex of the acinar cell. The cell is then stimulated by either a hormonal signal or a nerve impulse and the contents of the granules spill into a duct leading into the duodenum.^[1]

Chymotrypsinogen must be inactive until it gets to the digestive tract, so no damage is done to the pancreas or an other organs. It is activated into its active form by another enzyme called trypsin. This active form is called π-Chymotrypsin and is used to create α-Chymotrypsin. The trypsin cleaves the chymotrypsinogen at the arginine and isolucine peptide bond. This creates two π-chymotrypsin molecules. One of the π-chymotrypsin acts on the other by breaking a leucine and serine peptide bond. This yields the α-chymotrypsin.^[2]

References

Berg.M.J.,Tymoczko.L.J.,Stryer.L., Gatto Jr. J.G. Biochemistry, 7th Ed.; Freeman: New York, 2012.

Dryer.J.W.,Neurath.H. The Activation of Chemotyrpsinogen: ISOLATION AND IDENTIFICATION OF A PEPTIDE LIBERATED DURING ACTIVATION Department of Biochemistry, University of Washington [1955]http://www.jbc.org/content/217/2/527.full.pdf (accessed Oct. 10, 2012]

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^ http://www.jbc.org/content/217/2/527.full.pdf

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[2] ttp://www.jbc.org/content/217/2/527.full.pdf

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-'''Chymotrypsinogen''' is a precursor ([[zymogen]]) of the [[digestive enzyme]] [[chymotrypsin]].
-This [[molecule]] is inactive and must be cleaved by [[trypsin]], and then by other
+'''Chymotrypsinogen''' is a precursor ([[zymogen]]) of the [[digestive enzyme]] [[chymotrypsin]]. It is a single polypetide chain consisting of 245 amino acid residues. It is synthesized in the acinar cells of the pancreas and stored inside membrane-bounded granules at the apex of the acinar cell. The cell is then stimulated by either a hormonal signal or a nerve impulse and the contents of the granules spill into a duct leading into the [[duodenum]].<ref name=undefined />
-chymotrypsin molecules, before it can reach its full activity.  Its function is to convert [[protein]]s to smaller [[peptide]]s. The [[active site]] of chymotrypsinogen is covered by a 6-amino-acid-long mask. It is only when this mask is removed - when the chymotrypsinogen molecule enters the lumen of the intestine and comes into contact with trypsin molecules - that the enzyme becomes active. This is a very useful safety feature for a protein-digesting enzyme. If chymotrypsinogen were not inactivated in this way, it would digest the [[pancreas]], where it is produced.
+ Chymotrypsinogen must be inactive until it gets to the digestive tract, so no damage is done to the pancreas or an other organs. It is activated into its active form by another enzyme called [[trypsin]]. This active form is called π-Chymotrypsin and is used to create α-Chymotrypsin. The trypsin cleaves the chymotrypsinogen at the arginine and isolucine peptide bond. This creates two π-chymotrypsin molecules. One of the π-chymotrypsin acts on the other by breaking a leucine and serine peptide bond. This yields the α-chymotrypsin.<ref>http://www.jbc.org/content/217/2/527.full.pdf</ref>
 ==References==
 {{Unreferenced|date=January 2009}}
+Berg.M.J.,Tymoczko.L.J.,Stryer.L., Gatto Jr. J.G. ''Biochemistry'', 7th Ed.; Freeman: New York, 2012.
+Dryer.J.W.,Neurath.H. ''The Activation of Chemotyrpsinogen: ISOLATION AND IDENTIFICATION OF A PEPTIDE LIBERATED DURING ACTIVATION '' Department of Biochemistry, University of Washington [1955]http://www.jbc.org/content/217/2/527.full.pdf (accessed Oct. 10, 2012]
 [[Category:Enzymes]]
 {{enzyme-stub}}