Cystathionine beta-synthase

In enzymology, a cystathionine beta-synthase is an enzyme that catalyzes the chemical reaction


 * L-serine + L-homocysteine $$\rightleftharpoons$$ L-cystathionine + H2O

Thus, the two substrates of this enzyme are L-serine and L-homocysteine, whereas its two products are L-cystathionine and H2O.

This enzyme belongs to the family of lyases, specifically the hydro-lyases, which cleave carbon-oxygen bonds. The systematic name of this enzyme class is L-serine hydro-lyase (adding homocysteine; L-cystathionine-forming). Other names in common use include serine sulfhydrase, beta-thionase, methylcysteine synthase, cysteine synthase, serine sulfhydrylase, and L-serine hydro-lyase (adding homocysteine). This enzyme participates in 4 metabolic pathways: glycine, serine and threonine metabolism, methionine metabolism, selenoamino acid metabolism, and huntington's disease. It employs one cofactor, pyridoxal phosphate.

Structural studies
As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes and.