# NIH shift > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/NIH_shift > Markdown URL: https://mediated.wiki/source/NIH_shift.md > Source: https://en.wikipedia.org/wiki/NIH_shift > Source revision: 1336240992 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) An '''NIH shift''' is a chemical rearrangement where a hydrogen atom on an aromatic ring undergoes an [intramolecular](/source/Intramolecular_reaction) migration primarily during a [hydroxylation](/source/hydroxylation) reaction. This process is also known as a 1,2-hydride shift. These shifts are often studied and observed by [isotopic labeling](/source/isotopic_labeling). An example of an NIH shift is shown below: 400px|center|''Example of NIH shift'' In this example, a [hydrogen](/source/hydrogen) atom has been isotopically labeled using [deuterium](/source/deuterium) (shown in red). The process proceeds via an [arene oxide](/source/arene_oxide), which rearrange to give the diene-ketone via the NIH shift. This is the initial step in the detoxification of benzene by [cytochrome P450](/source/cytochrome_P450).{{cite journal |last1=Meunier |first1=Bernard |last2=De Visser |first2=Samuël P. |last3=Shaik |first3=Sason |title=Mechanism of Oxidation Reactions Catalyzed by Cytochrome P450 Enzymes |journal=Chemical Reviews |date=2004 |volume=104 |issue=9 |pages=3947–3980 |doi=10.1021/cr020443g |pmid=15352783 }} Several hydroxylase enzymes are believed to incorporate an NIH shift in their mechanism, including [4-hydroxyphenylpyruvate dioxygenase](/source/4-hydroxyphenylpyruvate_dioxygenase) and the [tetrahydrobiopterin](/source/tetrahydrobiopterin) dependent [hydroxylase](/source/hydroxylase)s. The name ''NIH shift'' arises from the US [National Institutes of Health](/source/National_Institutes_of_Health) from where studies first reported observing this transformation. == References == {{Reflist}} * {{cite journal |author1=Guroff, G. |author2=Daly, J.W. |author3=Jerina, D.M. |author4=Renson, J. |author5=Witkop, B. |author6=Udenfriend, S. | title=Hydroxylation-induced migration: the NIH shift. Recent experiments reveal an unexpected and general result of enzymatic hydroxylation of aromatic compounds. | journal=Science | year=1967 | volume=157 | pages=1524–1530 | pmid=6038165 | doi=10.1126/science.157.3796.1524 | issue=3796|bibcode = 1967Sci...157.1524G }}. * {{cite journal |author1=Bassan, A. |author2=Blomberg, M.R.A. |author3=Siegbahn, P.E.M. | title=Mechanism of Aromatic Hydroxylation by an Activated FeIV=O Core in Tetrahydrobiopterin-Dependent Hydroxylases | journal=Chem. Eur. J. | year=2003 | volume=9 | pages=4055–4067 | pmid=12953191 | doi=10.1002/chem.200304768 | issue=17}}. Category:Enzymes Category:Post-translational modification Category:Reaction mechanisms --- Adapted from the Wikipedia article [NIH shift](https://en.wikipedia.org/wiki/NIH_shift) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/NIH_shift?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.