Assay Method Information

Assay Name:  Tyrosinase Inhibition Assay
Description:  A tyrosinase inhibition assay was carried out using the method reported by Jones et al. (2002) Pigment. Cell Res. 15:335. Using this method, the conversion of L-Dopa, a substrate of tyrosinase, into dopachrome is followed by monitoring absorption at 450 nm. Tyrosinase was prepared in 50 mM potassium phosphate buffer, pH 6.8 (assay buffer) at 2000 U/ml and stored at −20° C. in 1 ml aliquots prior to use. For use in assays, stock enzyme solutions were thawed and diluted to 200 U/ml with assay buffer. A 2 mM working solution of substrate, L-DOPA, was prepared in assay buffer for each assay. Samples were dissolved in 10% DMSO (0.5 ml) and diluted to 5 ml with assay buffer. The reaction mixture consisted of 0.050 ml 2 mM L-DOPA, 0.050 ml 200 U/ml mushroom tyrosinase and 0.050 ml inhibitor. Reaction volume was adjusted to 200 μl with assay buffer. Assays were performed in 96 well Falcon 3097 flat-bottom microtiter plates (Beckton Dickinson, N.J.). Appearance of dopachrome was measured with a WALLAC 1420 Multilable Counter (Turku, Finland). Average velocity was determined from linear enzyme rate as measured by change in absorbance (ΔA450) at 450 nm per minute.
Affinity data for this assay
 

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