Cystathionine beta-synthase

Cystathionine beta-synthase (CBS) is an enzyme that in humans is encoded by the CBS gene. CBS catalyzes the first step of the transsulfuration pathway, from homocysteine to cystathionine.

Function

CBS converts homocysteine into cystathionine, the first step in the transsulfuration pathway. This pathway leads to the biosynthesis of cysteine, an amino acid that is a crucial part of many biological structures and processes.

Structure

The CBS enzyme is a tetramer, meaning it is composed of four subunits. Each subunit contains a pyridoxal phosphate (PLP) binding domain and a heme binding domain. The PLP binding domain is responsible for the enzyme's catalytic activity, while the heme binding domain regulates this activity.

Clinical significance

Mutations in the CBS gene can lead to cystathioninuria and homocystinuria, both of which are metabolic disorders that can have serious health consequences.

See also

• Transsulfuration pathway
• Homocysteine
• Cystathionine
• Cystathioninuria
• Homocystinuria