Cystathionine-β-lyase is primarily involved in the metabolism of sulfur-containing amino acids, playing a key role in the transsulfuration pathway. It catalyzes the breakdown of cystathionine into cysteine, α-ketobutyrate, and ammonia, making it essential for cysteine biosynthesis. This enzymatic activity supports the production of glutathione, a major cellular antioxidant, thereby contributing to oxidative stress defense.

In medical research, this enzyme is studied for its implications in homocystinuria and cardiovascular diseases due to its role in regulating homocysteine levels. Deficiency or dysfunction can lead to elevated homocysteine, a risk factor for thrombosis and atherosclerosis.

In biotechnology, Cystathionine-β-lyase is used in enzymatic assays and diagnostic kits to measure cystathionine or related metabolites in clinical samples. It is also explored for potential use in targeted cancer therapies, where modulating cysteine levels can influence tumor growth and response to chemotherapy.

Additionally, the enzyme has applications in microbial physiology studies, especially in bacteria like Escherichia coli and Mycobacterium tuberculosis, where it is a target for antimicrobial drug development due to its necessity in pathogen survival under host conditions.