Cystathionine

?-synthase Cystathionine ?-synthase (CBS) is an enzyme in humans and other organisms that plays an important role in the metabolism of sulfur-containing amino acids. It catalyzes the condensation of serine and homocysteine to form cystathionine. CBS is a key enzyme in the transsulfuration pathway, the process by which toxic homocysteine is converted to cystathionine, and then to harmless cysteine. In addition to its role in sulfur metabolism, CBS has also been linked to certain diseases, including certain forms of hypertension, Alzheimer's disease, and certain types of cancer. CBS has been used as an important therapeutic target, and its inhibition or stimulation has been used to treat disorders involving sulfur metabolism.