Extraction of Tyrosinase from Potatoes and Activation of Tyrosinase by Plant Essential Oils and Its Kinetics

The extraction and eaction of tryosinase from potato,and optimization by single factor experiment were been investigated in the study. The plant essential oil which could increase the catalytic activity of tryosinase was been screened by dopa rate oxidation method. Furthermore,enzyme kinetics model was used to study it's catalytic mechanism. Results showed that the optimal extraction conditions of tyrosinase in potatoes were as follows:solid-liquid ratio 1:10 (g/mL),phosphate buffer pH value 6.8. The optimum reaction conditions of tryosinase were as follows:reaction temperature 35℃,reaction time 13 min,and the substrate addition L-Dopa/crude enzyme addition ratio at 5:5. In the screening of 15 plant essential oils under the optimal extraction conditions and reaction conditions,thyme,tea tree and ylang-ylang had significant tryosinase activation(P>0.05),the IC₅₀ values were 0.488,0.429 and 0.480 mg/mL,close to the positive control psoralen IC₅₀ value 0.328 mg/mL. The kinetic experiments found that the activation types of thyme,tea tree and ylang-ylang oil were non-competitive,mixed and mixed.