title: Kinetic inactivation study of mushroom tyrosinase: intermediate detection by denaturants.
abstract: The unfolding and inhibition study of mushroom tyrosinase have been studied in the presence of different denaturants such as sodium dodecyl sulfate (SDS), guanidine hydrochloride (GdnHCl), and urea. The kinetic two-phase rate constants were commonly measured from semilogarithmic plots of the activity versus time, which resolved into two straight lines, indicating that the inactivation process consisted of fast and slow phases as a first-order reaction. This result also implied that transient partially folded intermediate existed during tyrosinase unfolding pathway. Mushroom tyrosinase had different behaviors to denaturants in regard with: noncooperative binding manner by SDS while cooperative interactions by GdnHCl and urea; in equilibrium state, SDS-micelle never completely inactivated enzyme activity while GdnHCl has single step denaturation and urea induced a typical transition-like process. Various kinetic parameters for each denaturant were calculated and the possible unfolding pathway scheme was discussed.
authors.affiliation: Clinical Research Center, Samsung Biomedical Research Institute, Seoul 135-710, Korea.
authors.forename: Yong-Doo
authors.initials: YD
authors.lastname: Park
authors.forename: Jae-Yong
authors.initials: JY
authors.lastname: Jung
authors.forename: Do-Won
authors.initials: DW
authors.lastname: Kim
authors.forename: Won-Serk
authors.initials: WS
authors.lastname: Kim
authors.forename: Myong-Joon
authors.initials: MJ
authors.lastname: Hahn
authors.forename: Jun-Mo
authors.initials: JM
authors.lastname: Yang
mesh_terms: D000364:Agaricus / Q000201:enzymology*; D002384:Catalysis / Q000187:drug effects; D019791:Guanidine / Q000494:pharmacology; D007700:Kinetics; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D011489:Protein Denaturation / Q000187:drug effects; D017510:Protein Folding; D012967:Sodium Dodecyl Sulfate / Q000494:pharmacology; D013816:Thermodynamics; D014508:Urea / Q000494:pharmacology
chemical_list: D012967:Sodium Dodecyl Sulfate; D014508:Urea; D014442:Monophenol Monooxygenase; D019791:Guanidine