Cystathionine

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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
KEGG
MeSH Cystathionine
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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Infobox references

Cystathionine is an intermediate in the synthesis of cysteine.

Cystathionine is produced by the transsulfuration pathway which converts homocysteine into cystathionine. Cystathionine is then used by the enzymes cystathionine gamma-lyase (CTH), cysteine dioxygenase (CDO), and cysteine sulfinic acid decarboxylase (CSAD) to produce 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.

An excess of cystathionine in the urine is called cystathioninuria.

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).

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

References[edit]

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