What does cystathionine beta-synthase do?

Cystathionine beta-synthase (CBS) is the first enzyme in the transsulfuration pathway, catalyzing the conversion of serine and homocysteine to cystathionine and water. The enzyme contains three functional domains.

What does the CBS enzyme do?

The CBS gene provides instructions for making an enzyme called cystathionine beta-synthase. This enzyme acts in a chemical pathway and is responsible for using vitamin B6 to convert building block of proteins (amino acid) called homocysteine and serine to a molecule called cytathionine.

Which of the following is a cofactor for Cystathionine B synthase?

CBS uses the cofactor pyridoxal-phosphate (PLP) and can be allosterically regulated by effectors such as the ubiquitous cofactor S-adenosyl-L-methionine (adoMet).

Which Gasotransmitter is produced by the Cystathionine β synthase enzyme?

Cystathionine β-synthase (CBS) catalyzes the condensation of serine (Ser) and Hcy into cystathionine (Cysth) and water. Alternative reactions catalyzed by CBS, using cysteine (Cys) alone or Cys and Hcy, result in H2S production.

What does homocysteine do in the body?

High homocysteine levels in the blood can damage the lining of the arteries. High levels may also make the blood clot more easily than it should. This can increase the risk of blood vessel blockages. A clot inside your blood vessel is called a thrombus.

What is CBS mutation?

This form of homocystinuria is caused by a genetic mutation in the CBS gene , which leads to low levels or absence of an enzyme called cystathionine beta-synthase (CBS). When CBS is absent or not working right, homocysteine and other toxic chemicals build up in the blood and urine.

How is CBS treated?

Treatment may include therapy with pyridoxine (vitamin B6), a diet that restricts the intake of protein and methionine, betaine therapy, and supplementation with folate (vitamin B9) or cobalamin (vitamin B12). Affected individuals may first undergo a pyridoxine response assessment.

What causes homocystinuria?

Mutations in the CBS gene cause the most common form of homocystinuria. The CBS gene provides instructions for producing an enzyme called cystathionine beta-synthase. This enzyme acts in a chemical pathway and is responsible for converting the amino acid homocysteine to a molecule called cystathionine.

What happens homocystinuria?

Homocystinuria (HCU) is a rare but potentially serious inherited condition. It means the body can’t process the amino acid methionine. This causes a harmful build-up of substances in the blood and urine.

What causes homocysteine to rise?

Most people who have a high homocysteine level don’t get enough folate (also called folic acid), vitamin B6, or vitamin B12 in their diet. Replacing these vitamins often helps return the homocysteine level to normal. Other possible causes of a high homocysteine level include: Low levels of thyroid hormone.

What is cystathionine β-synthase (CBS)?

Cystathionine β-synthase (CBS) is a key enzyme in the two-step biosynthesis of cysteine from homocysteine and serine and requires vitamin B 6 for its catalysis ( Fig. 39.1 ). This is the only pathway in humans that leads to cysteine production.

What enzyme converts homocysteine to cystathionine?

Cystathionine beta‐synthase, along with vitamin B 6, converts homocysteine to cystathionine (see Fig. 5‐8). A deficiency of this enzyme leads to accumulation not only of homocysteine but also its precursor, methionine. The genetic disorder, homocystinuria, is attributable to an abnormality on a gene on chromosome 21.

Why is cystathionine beta-synthase expressed in the radial glia?

Cystathionine beta-synthase, a key enzyme for homocysteine metabolism, is preferentially expressed in the radial glia/astrocyte lineage of developing mouse CNS Cystathionine beta-synthase (CBS; EC 4.2.1.22) is a key enzyme in the generation of cysteine from methionine.

How does cystathionine beta-synthase convert Hcy to GSH?

Cystathionine beta-synthase (CBS) converts HCY to GSH via the transsulfuration pathway with vitamin B6 as cofactor [53–55] ( Fig. 3.2 ). The tripeptide GSH is the main antioxidant and detoxification molecule. Keeping the balance between methylation and transsulfuration depends on methionine levels and allosteric activation of CBS by SAM.