title: Methods for measuring cysteine S-conjugate β-lyase activity.
abstract: The cysteine conjugate β-lyase represents activities in cytoplasm and mitochondria catalyzed by at least eleven pyridoxal 5'-phosphate (PLP)-dependent enzymes in various tissues. These enzymes mediate bioactivation of cysteine S-conjugates of several haloalkanes and haloalkenes. The reaction occurs through either a direct β-elimination or a transamination followed by a retro-Michael rearrangement, resulting in the cleavage of a C-S bond. The resultant product is a reactive thiolate that rearranges to form thioacylating species. This unit presents several protocols for the assay of β-lyase activity and includes measurements of product formation and substrate loss as well as fluorescent activity stains. Support protocols describe the synthesis and high-performance liquid chromatography analysis of selected cysteine S-conjugates. Because of the diversity of enzymes that can catalyze a β-lyase reaction, each of the assays presented here may indicate only a portion of the potential β-lyase activity in a given biological preparation.
authors.affiliation: Wayne State University School of Medicine, Detroit, Michigan, USA.
authors.forename: Lawrence H
authors.initials: LH
authors.lastname: Lash
mesh_terms: D000818:Animals; D052160:Benzothiazoles / Q000378:metabolism; D001681:Biological Assay / Q000379:methods*; D013437:Carbon-Sulfur Lyases / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003545:Cysteine / Q000031:analogs & derivatives / Q000378:metabolism; D003600:Cytosol / Q000201:enzymology; D006801:Humans; D008658:Inactivation, Metabolic; D008190:Lyases / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology; D004364:Pharmaceutical Preparations / Q000378:metabolism; D019289:Pyruvic Acid / Q000378:metabolism; D013053:Spectrophotometry / Q000379:methods; D000637:Transaminases / Q000378:metabolism
chemical_list: D052160:Benzothiazoles; D004364:Pharmaceutical Preparations; C034680:S-(2-benzothiazolyl)cysteine; D019289:Pyruvic Acid; D000637:Transaminases; C427605:glutamine - phenylpyruvate transaminase; D008190:Lyases; D013437:Carbon-Sulfur Lyases; C108902:cysteine-S-conjugate beta-lyase; D003545:Cysteine