Editing Proteolysis (section)

==Laboratory applications==
Proteolysis is also used in research and diagnostic applications: 
* Cleavage of [[fusion protein]] so that the fusion partner and [[protein tag]] used in [[Protein expression (biotechnology)|protein expression]] and [[Protein purification|purification]] may be removed. The proteases used have high degree of specificity, such as [[thrombin]], [[enterokinase]], and [[TEV protease]], so that only the targeted sequence may be cleaved.
* Complete inactivation of undesirable enzymatic activity or removal of unwanted proteins. For example, [[proteinase K]], a broad-spectrum proteinase stable in [[urea]] and [[Sodium dodecyl sulfate|SDS]], is often used in the preparation of [[nucleic acids]] to remove unwanted [[nuclease]] contaminants that may otherwise degrade the DNA or RNA.<ref>{{cite journal |vauthors=Hilz H, Wiegers U, Adamietz P |title=Stimulation of Proteinase K action by denaturing agents: application to the isolation of nucleic acids and the degradation of 'masked' proteins|journal=European Journal of Biochemistry|volume=56|issue=1|pages=103–108|year=1975|pmid=1236799|doi=10.1111/j.1432-1033.1975.tb02211.x|doi-access=free}}</ref>
* Partial inactivation, or changing the functionality, of specific protein. For example, treatment of [[DNA polymerase I]] with [[subtilisin]] yields the [[Klenow fragment]], which retains its polymerase function but lacks 5'-exonuclease activity.<ref>{{cite journal|vauthors=Klenow H, Henningsen I| title=Selective Elimination of the Exonuclease Activity of the Deoxyribonucleic Acid Polymerase from Escherichia coli B by Limited Proteolysis| journal= Proc. Natl. Acad. Sci. USA| volume= 65 |pages=168–175 | year=1970 | pmid=4905667 | doi = 10.1073/pnas.65.1.168 | issue=1| pmc=286206| bibcode=1970PNAS...65..168K| doi-access=free}}</ref>
* Digestion of proteins in solution for [[proteomics|proteome analysis]] by [[liquid chromatography-mass spectrometry]] (LC-MS). This may also be done by [[in-gel digestion]] of [[proteins]] after separation by [[gel electrophoresis]] for the identification by [[mass spectrometry]].
* Analysis of the stability of folded domain under a wide range of conditions.<ref>{{Cite journal|author= Minde DP|title= Determining biophysical protein stability in lysates by a fast proteolysis assay, FASTpp |journal= PLOS ONE |volume= 7 |pages= e46147 |year= 2012 |doi= 10.1371/journal.pone.0046147|issue= 10|editor1-last= Uversky|editor1-first= Vladimir N|last2= Maurice|first2= Madelon M.|last3= Rüdiger|first3= Stefan G. D.|pmid= 23056252|pmc= 3463568|bibcode= 2012PLoSO...746147M |doi-access= free }}</ref>
* Increasing success rate of crystallisation projects<ref>{{cite journal|pmid=19352432|year=2009|last1=Wernimont|first1=A|last2=Edwards|first2=A|title=In situ proteolysis to generate crystals for structure determination: An update|volume=4|issue=4|pages=e5094|doi=10.1371/journal.pone.0005094|pmc=2661377|journal=PLOS ONE|bibcode=2009PLoSO...4.5094W|editor1-last=Song|editor1-first=Haiwei|doi-access=free}}</ref>
* Production of digested protein used in growth media to culture bacteria and other organisms, e.g. [[tryptone]] in [[Lysogeny Broth]].