:Cystathionine

{{chembox

| Verifiedfields = changed

| Watchedfields = changed

| verifiedrevid = 443553935

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

| ImageFile = Cystathionin.svg

| ImageSize = 220

| ImageAlt = Skeletal formula of cystathionine

| ImageFile1 = Cystathionine zwitterion 3D ball.png

| ImageSize1 = 240px

| ImageAlt1=Ball-and-stick model of the cystathionine molecule as a zwitterion

| IUPACName=S-((R)-2-amino-2-carboxyethyl)-L-homocysteine

| OtherNames=L-Cystathionine; S-[(2R)-2-Amino-2-carboxyethyl]-L-homocysteine

|Section1={{Chembox Identifiers

| KEGG_Ref = {{keggcite|correct|kegg}}

| KEGG = C00542

| InChI = 1/C7H14N2O4S/c8-4(6(10)11)1-2-14-3-5(9)7(12)13/h4-5H,1-3,8-9H2,(H,10,11)(H,12,13)

| InChIKey = ILRYLPWNYFXEMH-UHFFFAOYAH

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

| ChEMBL = 209241

| StdInChI_Ref = {{stdinchicite|changed|chemspider}}

| StdInChI = 1S/C7H14N2O4S/c8-4(6(10)11)1-2-14-3-5(9)7(12)13/h4-5H,1-3,8-9H2,(H,10,11)(H,12,13)/t4-,5-/m0/s1

| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}}

| StdInChIKey = ILRYLPWNYFXEMH-WHFBIAKZSA-N

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

| CASNo=56-88-2

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

| UNII = 375YFJ481O

| PubChem=439258

| ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}}

| ChemSpiderID = 388392

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

| ChEBI = 17755

| SMILES = C(CSC[C@@H](C(=O)O)N)[C@@H](C(=O)O)N

| MeSHName=Cystathionine

}}

|Section2={{Chembox Properties

| C=7|H=14|N=2|O=4|S=1

| Appearance=

| Density=

| MeltingPt=

| BoilingPt=

| Solubility=

}}

|Section3={{Chembox Hazards

| MainHazards=

| FlashPt=

| AutoignitionPt =

}}

}}

Cystathionine is an intermediate in the synthesis of cysteine from homocysteine. It is produced by the transsulfuration pathway and is converted into cysteine by cystathionine gamma-lyase (CTH).

Biosynthetically, cystathionine is generated from homocysteine and serine by cystathionine beta synthase (upper reaction in the diagram below). It is then cleaved into cysteine and α-ketobutyrate by cystathionine gamma-lyase (lower reaction).

An excess of cystathionine in the urine is called cystathioninuria.

File:Cysteine biosynthesis unlabeled.svg catalyzes the upper reaction and cystathionine gamma-lyase catalyzes the lower reaction.]]{{clear-left}}

Cysteine dioxygenase (CDO), and sulfinoalanine decarboxylase can turn cysteine into hypotaurine and then taurine.{{ Cite journal | author = Harris Ripps, Wen Shen |date = 2012 | title = Review: Taurine: A "very essential" amino acid | journal = Molecular Vision |volume = 18 | pages = 2673–2686 | pmid=23170060 | pmc=3501277}} Alternately, the cysteine from the cystathionine gamma-lyase can be used by the enzymes glutamate–cysteine ligase (GCL) and glutathione synthetase (GSS) to produce glutathione.