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).

Cystathionine
Skeletal formula of cystathionine
Ball-and-stick model of the cystathionine molecule as a zwitterion
Names
IUPAC name
S-((R)-2-amino-2-carboxyethyl)-L-homocysteine
Other names
L-Cystathionine; S-[(2R)-2-Amino-2-carboxyethyl]-L-homocysteine
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.000.269 Edit this at Wikidata
KEGG
MeSH Cystathionine
UNII
  • InChI=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 ☒N
    Key: ILRYLPWNYFXEMH-WHFBIAKZSA-N ☒N
  • 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)
    Key: ILRYLPWNYFXEMH-UHFFFAOYAH
  • C(CSC[C@@H](C(=O)O)N)[C@@H](C(=O)O)N
Properties
C7H14N2O4S
Molar mass 222.26 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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.

Cysteine metabolism. Cystathionine beta synthase catalyzes the upper reaction and cystathionine gamma-lyase catalyzes the lower reaction.

Cysteine dioxygenase (CDO), and sulfinoalanine decarboxylase can turn cysteine into hypotaurine and then taurine.[1] 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.

References

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  1. ^ Harris Ripps, Wen Shen (2012). "Review: Taurine: A "very essential" amino acid". Molecular Vision. 18: 2673–2686. PMC 3501277. PMID 23170060.