Cystathionine β-synthase is an enzyme that plays a crucial role in the metabolism of sulfur-containing amino acids, particularly in the conversion of homocysteine to cystathionine. This process is essential for producing cysteine, which is important for protein synthesis and various cellular functions. Deficiency in cystathionine β-synthase can lead to a condition known as homocystinuria, characterized by elevated levels of homocysteine in the blood. This condition can result in various health issues, including cardiovascular problems and developmental delays, highlighting the enzyme's importance in maintaining metabolic balance.