Cystathionine beta-lyase

Cystathionine beta-lyase (CBL) is an enzyme that plays a crucial role in the metabolism of sulfur-containing amino acids. It is encoded by the CBL gene and is primarily found in the liver and kidneys of humans and other mammals. CBL is involved in the breakdown of cystathionine, an intermediate compound in the transsulfuration pathway.

Function

Cystathionine beta-lyase catalyzes the conversion of cystathionine into cysteine, alpha-ketobutyrate, and ammonia. This reaction is an essential step in the metabolism of methionine and cysteine, two sulfur-containing amino acids. By breaking down cystathionine, CBL helps regulate the levels of these amino acids in the body.

Clinical Significance

Mutations in the CBL gene can lead to a deficiency in cystathionine beta-lyase activity, resulting in a rare inherited disorder known as cystathionine beta-lyase deficiency. This condition is characterized by the accumulation of cystathionine and other toxic metabolites in the body. Symptoms of cystathionine beta-lyase deficiency can vary widely but often include intellectual disability, seizures, developmental delay, and other neurological problems.

Role in Homocystinuria

Cystathionine beta-lyase deficiency is one of the causes of homocystinuria, a metabolic disorder characterized by elevated levels of homocysteine in the blood. Homocystinuria can lead to various complications, including cardiovascular problems, skeletal abnormalities, and eye abnormalities. Treatment for homocystinuria often involves dietary modifications, such as restricting methionine intake and supplementing with vitamin B6.

See Also

• Transsulfuration pathway
• Methionine metabolism
• Cysteine metabolism