Tyrosinase Activity Assay

Tyrosinase activity assays were performed following the previous reports with minor modification (17–19). 1 g mantle tissue was homogenized in 3 ml of 0.1 mol/L Phosphate Buffered Saline (PBS, pH 6.8), and was centrifuged at 12,000g for 10 min to obtain the supernatant (about 1 ml). Then, 0.5 ml of 5 mmol/L 3, 4-dihydroxyphenylalanine (L-DOPA) was mixed with all the supernatant, and incubated at 37°C for 30 min. The absorbance of the mixture was recorded at 475 nm. The tryosinase activity was defined as increased or decreased absorbance in 30 min at 475 nm.