:Endomorphin-2

{{Chembox

| ImageFile = Endomorphin 2.svg

| ImageClass = skin-invert-image

| ImageSize = 250px

| IUPACName = L-Tyrosyl-L-prolyl-L-phenylalanyl-L-phenylalaninamide

| OtherNames =

|Section1={{Chembox Identifiers

| IUPHAR_ligand = 3668

| CASNo = 141801-26-5

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

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

| UNII = 3PH5M0466G

| PubChem = 5311081

| ChemSpiderID = 4470615

| SMILES = c1ccc(cc1)C[C@@H](C(=O)N)NC(=O)[C@H](Cc2ccccc2)NC(=O)[C@@H]3CCCN3C(=O)[C@H](Cc4ccc(cc4)O)N

| InChI = 1/C32H37N5O5/c33-25(18-23-13-15-24(38)16-14-23)32(42)37-17-7-12-28(37)31(41)36-27(20-22-10-5-2-6-11-22)30(40)35-26(29(34)39)19-21-8-3-1-4-9-21/h1-6,8-11,13-16,25-28,38H,7,12,17-20,33H2,(H2,34,39)(H,35,40)(H,36,41)/t25-,26-,27-,28-/m0/s1

| InChIKey = XIJHWXXXIMEHKW-LJWNLINEBE

| StdInChI = 1S/C32H37N5O5/c33-25(18-23-13-15-24(38)16-14-23)32(42)37-17-7-12-28(37)31(41)36-27(20-22-10-5-2-6-11-22)30(40)35-26(29(34)39)19-21-8-3-1-4-9-21/h1-6,8-11,13-16,25-28,38H,7,12,17-20,33H2,(H2,34,39)(H,35,40)(H,36,41)/t25-,26-,27-,28-/m0/s1

| StdInChIKey = XIJHWXXXIMEHKW-LJWNLINESA-N

}}

|Section2={{Chembox Properties

| Formula = C₃₂H₃₇N₅O₅

| MolarMass = 571.667 g/mol

| Appearance =

| Density =

| MeltingPt =

| BoilingPt =

| Solubility =

}}

|Section3={{Chembox Hazards

| MainHazards =

| FlashPt =

| AutoignitionPt =

}}

}}

Endomorphin-2 (EM-2) is an endogenous opioid peptide and one of the two endomorphins.{{cite book|author1=Richard J. Bodnar|author2=Kathryn Grace Commons|author3=Donald W. Pfaff|title=Central Neural States Relating Sex and Pain|url=https://books.google.com/books?id=4KeQEC4nHSkC&pg=PA67|date=3 April 2002|publisher=JHU Press|isbn=978-0-8018-6827-6|pages=67–}} It has the amino acid sequence Tyr-Pro-Phe-Phe-NH₂. It is a high affinity, highly selective agonist of the μ-opioid receptor, and along with endomorphin-1 (EM-1), has been proposed to be the actual endogenous ligand of this receptor (that is, rather than the endorphins).{{cite book|author1=H.-J. Krammer|author2=M.V. Singer|title=Neurogastroenterology - From the Basics to the Clinics|url=https://books.google.com/books?id=ghjN0L47QbwC&pg=PA76|date=31 May 2000|publisher=Springer Science & Business Media|isbn=978-0-7923-8757-2|pages=76–}}{{cite book|author1=Susan Brain|author2=P.K. Moore|title=Pain and Neurogenic Inflammation|url=https://books.google.com/books?id=6TNSAeTpkUMC&pg=PA28|year=1999|publisher=Springer Science & Business Media|isbn=978-3-7643-5875-4|pages=28–}}{{cite book|author1=Stefan Offermanns|author2=Walter Rosenthal|title=Encyclopedia of Molecular Pharmacology|url=https://books.google.com/books?id=fGe6NDIGQpsC&pg=PA904|date=14 August 2008|publisher=Springer Science & Business Media|isbn=978-3-540-38916-3|pages=904–}} Like EM-1, EM-2 produces analgesia in animals, but whereas EM-1 is more prevalent in the brain, EM-2 is more prevalent in the spinal cord. In addition, the action of EM-2 differs from that of EM-1 somewhat, because EM-2 additionally induces the release of dynorphin A and [Met]enkephalin in the spinal cord and brain by an unknown mechanism, which in turn activate the κ- and δ-opioid receptors, respectively, and a portion of the analgesic effects of EM-2 is dependent on this action.{{cite book|author1=William D. Willis Jr.|author2=Richard E. Coggeshall|title=Sensory Mechanisms of the Spinal Cord: Volume 1 Primary Afferent Neurons and the Spinal Dorsal Horn|url=https://books.google.com/books?id=uqnKCewO2voC&pg=PA343|date=31 January 2004|publisher=Springer Science & Business Media|isbn=978-0-306-48033-1|pages=343–}}{{cite book|author=Austin|title=Zen-Brain Reflections|date=24 September 2010|url=https://books.google.com/books?id=uZ4fyfH_t9EC&pg=PA125|publisher=MIT Press|isbn=978-0-262-26037-4|pages=125–}} Moreover, while EM-1 produces conditioned place preference, a measure of drug reward, EM-2 produces conditioned place aversion, an effect which is dynorphin A-dependent. Similarly to the case of EM-1, the gene encoding for EM-2 has not yet been identified.{{cite book|author=Brian E. Cairns|title=Peripheral Receptor Targets for Analgesia: Novel Approaches to Pain Management|url=https://books.google.com/books?id=MTSvERxiCrIC&pg=PA520|date=1 September 2009|publisher=John Wiley & Sons|isbn=978-0-470-52221-9|pages=520–}}