Abstract:Tyrosinase inhibitors can inhibit the synthesis of melanin and are widely applied in cosmetic，medical，and food industries.In this study，peptides from fish scales were used as raw materials，and the peptides were ultrasonic treated in advance.The ultrasonic process parameters were optimized through single factor test，and the peptide concentration of 0.14 g/mL，the ultrasonic power of 600 W，and the ultrasonic temperature of 55 ℃ were selected.Subsequently，the tilapia scale polypeptides were chelated with copper ions.Tilapia scale polypeptides were treated by enzymatic hydrolysis，column chromatography，and elution with ethylene diamine tetraacetic acid，and then the polypeptides with copper ion chelating ability were obtained.The tyrosinase inhibitory activity showed that the polypeptides strongly inhibited the activity of tyrosinase.When the concentration of the polypeptide sample was 5 mg/mL，the inhibition rate reached 60.0%.The comprehensive results indicated that the fish scale polypeptides with copper ion chelating ability could serve as a strong tyrosinase inhibitor.The binding of each polypeptide sequence in the component was identified and analyzed by nano-high performance liquid chromatography-tandem mass spectrometry（nano-HPLC-MS/MS）to the metal copper ions at the active center of tyrosinase.The inhibitory mechanism of this component on tyrosinase was determined to compete with the ligand of the enzyme for the metal copper ions in the active center.Through destroying the active center of tyrosinase，the enzyme activity was inhibited.The comprehensive results indicated that the fish scale polypeptides with copper ion chelating ability could serve as a strong tyrosinase inhibitor.