title: Inhibition of cathepsin B activity by 2,3,7,8-tetrachlorodibenzo-p-dioxin.
abstract: 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is the most potent toxic isomer in the dioxin-like family. Due to its resistance to metabolic degradation, this ubiquitous environmental pollutant readily accumulates in multiple organs. Cathepsin B is a lysosomal cysteine protease playing an essential role in the intracellular protein turnover. Alterations in its expression, activity, and localization may facilitate the development of many pathologies, including cancer. TCDD, due to its extremely lipophilic nature, may diffuse through biological membranes and affect lysosomal enzymes, including cathepsins. Therefore, in this study we performed two enzymatic assays, spectrofluorimetry and gelatin zymography, in order to evaluate the effect of TCDD on purified bovine cathepsin B. We showed that the dioxin decreases the enzyme's activity in a dose-dependent manner. The reversibility of TCDD-induced inhibition of the protease was also examined, suggesting that TCDD does not bind covalently to the enzyme's active site, acting rather as a reversible inhibitor.
authors.affiliation: Department of Physical Chemistry of Microorganisms, Institute of Genetics and Microbiology, University of Wrocław, Przybyszewskiego 63/77, 51-148, Wrocław, Poland.
authors.forename: Mateusz
authors.initials: M
authors.lastname: Kędzior
authors.forename: Rafał
authors.initials: R
authors.lastname: Seredyński
authors.forename: Urszula
authors.initials: U
authors.lastname: Godzik
authors.forename: Dagmara
authors.initials: D
authors.lastname: Tomczyk
authors.forename: Jan
authors.initials: J
authors.lastname: Gutowicz
authors.forename: Ewa
authors.initials: E
authors.lastname: Terlecka
authors.forename: Ireneusz
authors.initials: I
authors.lastname: Całkosiński
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Terlecki
mesh_terms: D000818:Animals; D002401:Cathepsin B / Q000037:antagonists & inhibitors*; D002417:Cattle; D004147:Dioxins; D006801:Humans; D000072317:Polychlorinated Dibenzodioxins / Q000633:toxicity*
chemical_list: D004147:Dioxins; D000072317:Polychlorinated Dibenzodioxins; D002401:Cathepsin B