Editing Proline (section)

{{Other uses}}
{{Distinguish|Prolene}}
{{Chembox
| ImageFileL2 = Prolin - Proline.svg
| ImageNameL2 = Structural formula of proline
| ImageClassL2 = skin-invert-image
| ImageFileR2 = L-Proline.svg
| ImageCaption = [[skeletal formula]] of proline
| ImageClassR2 = skin-invert-image
| ImageFileL3 = Proline-from-xtal-3D-bs-17-view-B.png
| ImageClassL3 = bg-transparent
| ImageCaptionL3 = [[ball-and-stick model]]
| ImageFileR3 = Proline-from-xtal-3D-sf-view-B.png
| ImageClassR3 = bg-transparent
| ImageCaptionR3 = [[space-filling model]]
| IUPACName = Proline
| SystematicName = Pyrrolidine-2-carboxylic acid<ref>{{cite web| url= https://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=614&loc=ec_rcs |title=Proline| work = PubChem |publisher = U.S. National Library of Medicine |access-date=8 May 2018|url-status=live|archive-url=https://web.archive.org/web/20140116114913/http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=614&loc=ec_rcs|archive-date=16 January 2014}}</ref>
|Section1={{Chembox Identifiers
| index1_label = D/L
| index2_label = D
| index_label = L <!-- needs to be L (natural isomer) so drugbank etc. take correct index_label -->
| CASNo1 = 609-36-9
| CASNo1_Ref = {{cascite|correct|CAS}}
| CASNo2 = 344-25-2
| CASNo2_Ref = {{cascite|correct|CAS}}
| CASNo = 147-85-3
| CASNo_Ref = {{cascite|correct|CAS}}
| PubChem1 = 614
| PubChem2 = 8988
| PubChem = 145742
| ChemSpiderID1 = 594
| ChemSpiderID1_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID2 = 8640
| ChemSpiderID2_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 128566
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| UNII1 = DCS9E77JPQ
| UNII1_Ref = {{fdacite|correct|FDA}}
| UNII2_Ref = {{fdacite|correct|FDA}}
| UNII2 = L01Q4LGZ5L
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 9DLQ4CIU6V
| EINECS = 210-189-3
| DrugBank_Ref = {{drugbankcite|correct|drugbank}}
| DrugBank = DB00172
| KEGG = C00148
| KEGG_Ref = {{keggcite|correct|kegg}}
| MeSHName = Proline
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 17203
| ChEBI1_Ref = {{ebicite|correct|EBI}}
| ChEBI1 = 26271
| ChEBI2_Ref = {{ebicite|correct|EBI}}
| ChEBI2 = 16313
| ChEMBL = 72275
| ChEMBL_Ref = {{ebicite|correct|EBI}}
| RTECS = TW3584000
| Beilstein = 80812
| Gmelin = 26927
| SMILES = C1C[C@H](NC1)C(=O)O
| SMILES3 = [O-]C(=O)[C@H](CCC2)[NH2+]2
| SMILES3_Comment = L [[Zwitterion]]
| StdInChI = 1S/C5H9NO2/c7-5(8)4-2-1-3-6-4/h4,6H,1-3H2,(H,7,8)/t4-/m0/s1
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = ONIBWKKTOPOVIA-BYPYZUCNSA-N
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| InChIKey1 = ONIBWKKTOPOVIA-UHFFFAOYSA-N
| InChIKey2 = ONIBWKKTOPOVIA-SCSAIBSYSA-N
}}
|Section2={{Chembox Properties
| C = 5
| H = 9
| N = 1
| O = 2
| Appearance = Transparent crystals
| MeltingPtC = 205 to 228
| MeltingPt_notes = (decomposes)
| LogP = −0.06
| pKa=1.99 (carboxyl), 10.96 (amino)<ref>{{cite book | vauthors = Nelson DL, Cox MM | title = Principles of Biochemistry | location = New York | publisher = W.H. Freeman and Company }}</ref>
| SolubleOther = 1.5g/100g ethanol 19 degC<ref>{{cite book |title=Food Chemistry | vauthors = Belitz HD, Grosch W, Schieberle P |isbn= 978-3-540-69933-0 |page=15 |url=https://books.google.com/books?id=xteiARU46SQC&q=proline&pg=PA15 |url-status=live |archive-url=https://web.archive.org/web/20160515000801/https://books.google.com/books?id=xteiARU46SQC&pg=PA15&lpg=PA15&dq=proline&redir_esc=y#v=onepage&q=proline&f=false |archive-date=2016-05-15 |date=2009-01-15 | publisher = Springer }}
</ref>
}}
|Section3={{Chembox Hazards
}}
}}
[[File:Proline-spin.gif|thumb|Proline ball and stick model spinning]]
'''Proline''' (symbol '''Pro''' or '''P''')<ref>{{cite web| url = http://www.chem.qmul.ac.uk/iupac/AminoAcid/AA1n2.html | title = Nomenclature and Symbolism for Amino Acids and Peptides | publisher = IUPAC-IUB Joint Commission on Biochemical Nomenclature | year = 1983 | access-date = 5 March 2018| archive-url= https://web.archive.org/web/20081009023202/http://www.chem.qmul.ac.uk/iupac/AminoAcid/AA1n2.html| archive-date= 9 October 2008 | url-status= dead}}</ref> is an organic acid classed as a [[proteinogenic amino acid]] (used in the [[Protein biosynthesis|biosynthesis of proteins]]), although it does not contain the [[amino group]] {{chem|-NH|2}} but is rather a [[secondary amine]]. The secondary amine nitrogen is in the protonated form (NH<sub>2</sub><sup>+</sup>) under biological conditions, while the [[carboxyl group]] is in the [[deprotonated]] −COO<sup>−</sup> form. The "side chain" from the [[Alpha and beta carbon|α carbon]] connects to the nitrogen forming a [[pyrrolidine]] loop, classifying it as a [[aliphatic]] [[amino acid]]. It is non-essential in humans, meaning the body can synthesize it from the non-essential amino acid <small>L</small>-[[glutamate]]. It is [[Genetic code|encoded]] by all the [[codon]]s starting with CC (CCU, CCC, CCA, and CCG).

Proline is the only proteinogenic [[secondary amino acid|amino acid which is a secondary amine]], as the nitrogen atom is attached both to the α-carbon and to a chain of three carbons that together form a five-membered ring.