title: A new continuous spectrophotometric assay method for DOPA oxidase activity of tyrosinase.
abstract: Sensitive assay methods for tyrosinase are essential not only for the understanding the process of pigment production but also for the development of effective inhibitors of tyrosinase. To develop an efficient assay method, we applied thymol blue to reaction mixtures. The enzyme kinetic study revealed that DOPA oxidase activity of tyrosinase in thymol blue-applied reaction system was more sensitively measured, even under lower enzyme units compared with the previous report with significant enhancement of Vmax while affinity change on substrate was not observed. To test whether this method could be applicable to the inhibition and the inactivation kinetic study of tyrosinase, the effect of kojic acid, a well-known tyrosinase inhibitor, and sodium chloride respectively, have been studied. Conclusively, thymol blue method can assay tyrosinase activity with sensitivity and is applicable to the inhibition and the inactivation study of tyrosinase.
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-Rin
authors.initials: JR
authors.lastname: Lee
authors.forename: Kyung-Hee
authors.initials: KH
authors.lastname: Park
authors.forename: Hwa-Sun
authors.initials: HS
authors.lastname: Hahn
authors.forename: Myong-Joon
authors.initials: MJ
authors.lastname: Hahn
authors.forename: Jun-Mo
authors.initials: JM
authors.lastname: Yang
mesh_terms: D000363:Agaricales / Q000201:enzymology; D002021:Buffers; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D014442:Monophenol Monooxygenase / Q000378:metabolism*; D010710:Phosphates / Q000494:pharmacology; D011753:Pyrones / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology; D013053:Spectrophotometry / Q000379:methods*; D013944:Thymolphthalein / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D002021:Buffers; D010710:Phosphates; D011753:Pyrones; D012965:Sodium Chloride; C011890:kojic acid; C013713:thymol blue; D014442:Monophenol Monooxygenase; C018279:sodium phosphate; D013944:Thymolphthalein