Purification and partial characterization of tyrosinase from straw mushroom

Abstract

Tyrosinase from straw mushroom was purified to homogeneity in a two step procedure. After purification, the enzyme purity was increased by 4.81 fold with a specific activity of 9.68 unit/mg protein and the recovery yield of 0.12%. The molecular mass of purified tyrosinase estimated by SDS-PAGE electrophoresis was approximately 31 kDa. The purified tyrosinase showed the highest activity at pH 8.0 and 60 °C. The activity of the enzyme was enhanced by the addition of 10 mM Cu2+ or Zn2+ whereas the EDTA and 1,10-phenanthroline strongly inhibited the activity. The apparent Km and Vmax of the purified tyrosinase for L-DOPA at pH 8.0 and 60 °C were calculated to be 7.08 mM, 1.2 μM min–1and the apparent catalytic constant (kcat) was 1651 min–1.