[[File:Biuret Test 2.jpg|thumb|alt=A footbal containing air clear mauve solution|V zgornji epruveti je vidna rožnata barva, ki nakazuje na pozitivno reakcijo biuretskega testa.|250x250px]]
'''Biuretski test''' ('''Biuretskabiuretska reakcija''') ali '''Piotrowskijev test''' je [[Kvalitativna analiza|kvalitativni kemijski test]], ki se uporablja za dokazovanje prisotnosti [[Peptidna vez|peptidnih vezi]], značilnih za [[Beljakovina|beljakovine]]. V prisotnosti beljakovin [[Baker|bakrovi]] (II) [[Ion|ioni]] tvorijo rožnato obarvan kompleks.<ref> {{Cite web|title=Definition of biuret {{!}} Dictionary.com|url=https://www.dictionary.com/browse/biuret|access-date=2021-03-11|website=www.dictionary.com|language=en}}</ref><ref>The reaction was first observed 1833: Ferdinand Rose (1833) "Über die Verbindungen des Eiweiss mit Metalloxyden" (On the compounds of albumin with metal oxides), Poggendorfs ''Annalen der Physik und Chemie'', vol. 104, pages 132-142, {{DOI|10.1002/andp.18331040512}}. It was independently rediscovered in 1857 by a Polish physiologist: G. Piotrowski (1857) "Eine neue Reaction auf Eiweisskörper und ihre näheren Abkömmlinge" (A new reaction of proteins and their related derivatives) ''Sitzungsberichte der Kaiserliche Akademie der Wissenschaften in Wien, mathematisch-naturwissenschaftliche Classe'' (Proceedings of the Imperial Academy of Philosophies in Vienna, mathematical-natural sciences section), vol. 24, pages 335-337.</ref><ref name=":0">{{Navedi splet|title=Biuret test-Principle, Requirements, Reagents, Preparation, Procedure and Result|url=https://www.onlinebiologynotes.com/biuret-test-principle-requirements-reagents-preparation-procedure-and-result/|website=Online Biology Notes|date=2018-04-20|accessdate=2021-05-11|language=en-US|first=Gaurab|last=Karki}}</ref><ref name=":4">{{Navedi revijo|date=2005-01-01|title=PROTEINS {{!}} Physiological Samples|url=https://www.sciencedirect.com/science/article/pii/B0123693977004945|language=en|pages=357–375|doi=10.1016/B0-12-369397-7/00494-5}}</ref> Metoda je svoje ime dobila po snovi, ki se imenuje [[biuret]] (H{{Sub|2}}NCONHCONH{{Sub|2}}), in nastaja ob segrevanju [[Sečnina|sečnine]].<ref name=":6">{{Navedi splet|title=biuret test|url=https://www.oxfordreference.com/view/10.1093/oi/authority.20110803095509834|website=Oxford Reference|accessdate=2021-05-11|doi=10.1093/oi/authority.20110803095509834|language=en}}</ref> Na Poljskem je biuretski test v čast poljskemu [[Fiziologija|fiziologu]] [[Gustaw Piotrowski|Gustawu Piotrowskijevemu]], ki je metodo opisal leta 1857, poznan tudi pod imenom Piotrowskijev test.<ref>{{cite journal |last1=Dr. G. von Piotrowski |title=Eine neue Reaction auf Eiweisskörper und ihre näheren Abkömmlinge |journal=Sitzungsberichte der Kaiserlichen Akademie der Wissenschaften. Mathematisch-Naturwissenschaftliche Classe |date=1857 |volume=24 |page=335-337 |url=http://www.biodiversitylibrary.org/page/6896337}}</ref><ref name=":7">{{Navedi splet|title=Biuret Test|url=https://www.vedantu.com/chemistry/biuret-test|website=VEDANTU|accessdate=2021-05-11|language=en}}</ref> Pri reakciji se bakrovi (II) ioni vežejo z [[Atom|atomi]] peptidne vezi (skupina -CONH-).<ref name=":1">{{Navedi splet|title=Biuret Test for Protein {{!}} Biochemistry|url=https://microbenotes.com/biuret-test-for-protein/|website=Microbe Notes|date=2020-05-04|accessdate=2021-05-11|language=en-US}}</ref><ref name=":2" />
Iz osnovne različice so razvili več različic tega testa.<ref>“Chemistry of Protein Assay” Thermo Scientific Protein Methods Library. http://www.piercenet.com</ref> Biuretski test je najprimernejši za analiziranje [[Tkivo|tkivnih]] delcev, v katerih je visoka koncentracija beljakovin, saj je neobčutljiv za prisotnost prostih [[Aminokislina|aminokislin]] (te nimajo peptidne vezi, ki se vzpostavi komaj s povezavo dveh aminokislin v [[dipeptid]]<ref>{{Navedi splet|title=Peptide bond formation|url=https://www.mun.ca/biology/scarr/iGen3_06-03.html|website=www.mun.ca|accessdate=2021-05-11}}</ref><ref name=":1" />).<ref name=":2">{{Cite book|title=Fundamental Laboratory Approaches for Biochemistry and Biotechnology|last1=Ninfa|first1=Alexander|last2=Ballou|first2=David|last3=Benore|first3=Marilee|publisher=Wiley|year=2009|isbn=978-0470087664|pages=111}}</ref><ref name=":6" /> Med aminokislinami je izjema [[histidin]], ki prav tako daje pozitivno reakcijo.<ref>{{Navedi revijo|date=1963-07-01|title=Reaction of histidine with the biuret reagent in the presence of oxygen|url=https://www.sciencedirect.com/science/article/abs/pii/0003269763900022|magazine=Analytical Biochemistry|language=en|volume=6|issue=1|pages=1–12|doi=10.1016/0003-2697(63)90002-2|issn=0003-2697}}</ref><ref name=":0" /><ref name=":7" /> Pogosto se testa poslužujejo v analitski biomedicini pri dokazovanju beljakovin v [[Urin|urinu]] (seču).<ref name=":7" /><ref>{{Navedi revijo|last=Savory|first=John|last2=Pu|first2=Pin H|last3=Sunderman|first3=F William, Jr.|date=1968-12-01|title=A Biuret Method for Determination of Protein in Normal Urine|url=https://doi.org/10.1093/clinchem/14.12.1160|magazine=Clinical Chemistry|volume=14|issue=12|pages=1160–1171|doi=10.1093/clinchem/14.12.1160|issn=0009-9147}}</ref><ref>{{Navedi revijo|last=Guobing|first=Xu|last2=Lili|first2=Jiao|last3=Lihua|first3=Zhu|last4=Tiean|first4=Xia|date=2001|title=Application of an improved biuret method to the determination of total protein in urine and cerebrospinal fluid without concentration step by use of Hitachi 7170 auto-analyzer|url=https://onlinelibrary.wiley.com/doi/abs/10.1002/jcla.1020|magazine=Journal of Clinical Laboratory Analysis|language=en|volume=15|issue=4|pages=161–164|doi=10.1002/jcla.1020|issn=1098-2825|pmc=PMC6807869|pmid=11436195}}</ref>
