Cystathionine-β-Synthase (CBS) Activity Fluorometric Assay Kit

Cystathionine-β-synthase (CBS， EC 4.2.1.22) is a pyridoxal phosphate-dependent enzyme and a key enzyme in the transsulfuration pathway. The transsulfuration pathway is a crucial metabolic pathway for sulfur-containing amino acids， primarily responsible for converting homocysteine into cysteine， while also producing active sulfur metabolites such as hydrogen sulfide (H2S) and glutathione. In the presence of pyridoxal phosphate and S-adenosylmethionine， CBS catalyzes the formation of cystathionine and H2S from cysteine and homocysteine. The aromatic azide moiety of 7-azido-4-methylcoumarin (AzMC) is selectively reduced in the presence of H2S， producing the fluorescent 7-amino-4-methylcoumarin (AMC) with a concomitant increase in fluorescence with an excitation wavelength of 355 nm and an emission wavelength of 445 nm. The fluorescence intensity of AMC is directly proportional to H2S content. CBS activity can be calculated based on this relationship.