Cystathionine

Cystathionine is an intermediate in the synthesis of cysteine.

Contents

• Bich 411 project 4 cystathionine beta synthase
• Cystathionine gamma lyase deficiency group 9
• References

Cystathionine is produced by the Transsulfuration pathway which converts homocysteine into cystathionine. The cystathionine is then used by the Cystathionine gamma-lyase CTH, Cysteine dioxygenase CDO, and Cysteine sulfinic acid decarboxylase CSAD gene enzymes to produce hypotaurine and then taurine.

Alternately the Cysteine from the Cystathionine gamma-lyase CTH gene enzyme can be used by the Glutamate–cysteine ligase GCL and Glutathione synthetase GSS gene enzymes 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).