# Photoaffinity labeling

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{{Short description|Molecular biology technique}}
'''Photoaffinity labeling''' is a [chemoproteomics](/source/chemoproteomics) technique used to attach "labels" to the active site of a large molecule, especially a [protein](/source/protein). The "label" attaches to the molecule loosely and reversibly, and has an inactive site which can be converted using [photolysis](/source/photolysis) into a highly reactive form, which causes the label to bind more permanently to the large molecule via a covalent bond.<ref>[https://www.merriam-webster.com/medical/photoaffinity%20labeling Photoaffinity labeling]</ref><ref>[https://goldbook.iupac.org/P04578.html Photoaffinity labeling], [Gold Book](/source/Gold_Book)</ref> The technique was first described in the 1970s.<ref>{{Cite journal 
| doi = 10.1073/pnas.70.9.2567 
| last1 = Ruoho | first1 = A. E. 
| last2 = Kiefer | first2 = H. 
| last3 = Roeder | first3 = P. E. 
| last4 = Singer | first4 = S. J. 
| title = The mechanism of photoaffinity labeling 
| journal = Proceedings of the National Academy of Sciences of the United States of America 
| volume = 70 
| issue = 9 
| pages = 2567–2571 
| year = 1973 
| pmid = 4517671 
| pmc = 427057
| bibcode = 1973PNAS...70.2567R | doi-access = free }}</ref> Molecules that have been used as labels in this process are often analogs of complex molecules, in which certain functional groups are replaced with a photoreactive group, such as an [azide](/source/azide), a [diazirine](/source/diazirine) or a [benzophenone](/source/benzophenone).<ref>{{Cite journal 
| last1 = Bush | first1 = J. T. 
| last2 = Walport | first2 = L. J. 
| last3 = McGouran | first3 = J. F. 
| last4 = Leung | first4 = I. K. H. 
| last5 = Berridge | first5 = G. 
| title = The Ugi four-component reaction enables expedient synthesis and comparison of photoaffinity probes 
| doi = 10.1039/C3SC51708J
| journal = Chemical Science
| volume = 4
| issue = 12
| pages = 4115–4120 
| year = 2013 
| pmid = 
| pmc = 
| doi-access = free}}</ref><ref>{{Cite journal 
| last1 = Panov | first1 = M. S. 
| last2 = Voskresenska | first2 = V. D. 
| last3 = Ryazantsev | first3 = M. N. 
| last4 = Tarnovsky | first4 = A. N. 
| last5 = Wilson | first5 = R. M. 
| title = 5-Azido-2-aminopyridine, a New Nitrene/Nitrenium Ion Photoaffinity Labeling Agent That Exhibits Reversible Intersystem Crossing between Singlet and Triplet Nitrenes 
| doi = 10.1021/ja405637b 
| journal = Journal of the American Chemical Society 
| volume = 135 
| issue = 51 
| pages = 19167–19179 
| year = 2013 
| pmid = 24219134 
| pmc = 
| bibcode = 2013JAChS.13519167P 
| url = https://scholarworks.bgsu.edu/chem_pub/182 
| url-access = subscription 
}}</ref><ref>{{Cite journal 
| last1 = Akiyama | first1 = S. 
| last2 = Cornwell | first2 = M. M. 
| last3 = Kuwano | first3 = M. 
| last4 = Pastan | first4 = I. 
| last5 = Gottesman | first5 = M. M. 
| title = Most drugs that reverse multidrug resistance also inhibit photoaffinity labeling of P-glycoprotein by a vinblastine analog 
| journal = Molecular Pharmacology 
| volume = 33 
| issue = 2 
| pages = 144–147 
| year = 1988 
| pmid = 2893251
}}</ref>

==References==
{{Reflist}}

Category:Molecular biology techniques

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Adapted from the Wikipedia article [Photoaffinity labeling](https://en.wikipedia.org/wiki/Photoaffinity_labeling) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Photoaffinity_labeling?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.