2-Aminopurine

{{chembox

| Verifiedfields = changed

| Watchedfields = changed

| verifiedrevid = 477212531

| Name = 2-Aminopurine

| ImageFile_Ref = {{chemboximage|correct|??}}

| ImageFile = 2-Aminopurine.svg

| ImageSize = 230px

| ImageName = 2-Aminopurine

| PIN = 9H-Purin-2-amine

| Section1 = {{Chembox Identifiers

| InChI = 1/C5H5N5/c6-5-7-1-3-4(10-5)9-2-8-3/h1-2H,(H3,6,7,8,9,10)

| InChIKey = MWBWWFOAEOYUST-UHFFFAOYAC

| ChEMBL_Ref = {{ebicite|correct|EBI}}

| ChEMBL = 388594

| StdInChI_Ref = {{stdinchicite|correct|chemspider}}

| StdInChI = 1S/C5H5N5/c6-5-7-1-3-4(10-5)9-2-8-3/h1-2H,(H3,6,7,8,9,10)

| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

| StdInChIKey = MWBWWFOAEOYUST-UHFFFAOYSA-N

| CASNo_Ref = {{cascite|correct|CAS}}

| CASNo = 452-06-2

| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = O14B3U97FW

| PubChem = 9955

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| ChemSpiderID= 9561

| ChEBI_Ref = {{ebicite|correct|EBI}}

| ChEBI = 479072

| SMILES = Nc2ncc1nc[nH]c1n2

}}

| Section2 = {{Chembox Properties

| C=5|H=5|N=5

}}

}}

2-Aminopurine (2AP), a purine analog of guanine and adenine, is a fluorescent molecular marker used in nucleic acid research.{{cite journal |vauthors=Jean JM, Hall KB |title=2-Aminopurine fluorescence quenching and lifetimes: role of base stacking |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=98 |issue=1 |pages=37–41 |year=2001 |pmid=11120885 |url=http://www.pnas.org/cgi/pmidlookup?view=long&pmid=11120885 |doi=10.1073/pnas.011442198 |pmc=14540|doi-access=free }}{{cite journal |last1=Hall |first1=Kathleen B. |title=2-Aminopurine as a Probe of RNA Conformational Transitions |journal=Methods in Enzymology |date=2009 |volume=469 |pages=269–285 |doi=10.1016/S0076-6879(09)69013-3}} It most commonly pairs with thymine as an adenine-analogue. It uses a different ketone oxygen on thymine for H-bonding and forms a stronger bond.{{cite journal |last1=Hopfinger |first1=MC |last2=Kirkpatrick |first2=CC |last3=Znosko |first3=BM |title=Predictions and analyses of RNA nearest neighbor parameters for modified nucleotides. |journal=Nucleic Acids Research |date=18 September 2020 |volume=48 |issue=16 |pages=8901–8913 |doi=10.1093/nar/gkaa654 |pmid=32810273 |pmc=7498315}}

It can also pair with cytosine at low pH in a protonated wya like a functional analogue of guanine.{{cite journal |vauthors=Sowers LC, Fazakerley GV, Eritja R, Kaplan BE, Goodman MF |title=Base pairing and mutagenesis: observation of a protonated base pair between 2-aminopurine and cytosine in an oligonucleotide by proton NMR |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=83 |pages=5434–5438| year=1986 |doi=10.1073/pnas.83.15.5434 |pmid=3461441 |issue=15 |pmc=386301|bibcode=1986PNAS...83.5434S |doi-access=free }} For this reason it is sometimes used in the laboratory for mutagenesis. A mixture of structures are present according to NMR.{{cite journal |last1=Sowers |first1=LC |last2=Boulard |first2=Y |last3=Fazakerley |first3=GV |title=Multiple structures for the 2-aminopurine-cytosine mispair. |journal=Biochemistry |date=27 June 2000 |volume=39 |issue=25 |pages=7613–20 |doi=10.1021/bi992388k |pmid=10858312}} An atomic-resolution structures of the 2AP·C pair has been produced.{{cite journal |last1=Reha-Krantz |first1=LJ |last2=Hariharan |first2=C |last3=Subuddhi |first3=U |last4=Xia |first4=S |last5=Zhao |first5=C |last6=Beckman |first6=J |last7=Christian |first7=T |last8=Konigsberg |first8=W |title=Structure of the 2-aminopurine-cytosine base pair formed in the polymerase active site of the RB69 Y567A-DNA polymerase. |journal=Biochemistry |date=22 November 2011 |volume=50 |issue=46 |pages=10136–49 |doi=10.1021/bi2014618 |pmid=22023103}}