Abstract:

Myrosinase gene TGG1 of Arabidopsis thaliana was cloned and overexpressed in Pichia pastoris. The recombinant protein of TGG1 was purified with Ni-NTA.The recombinant protein has a molecular weight of 78 kD, larger than the deduced naked protein (58 kD), but similar to the molecular weight of the natural TGG1 protein. The TGG1 signal peptide has some secretion function in yeast, resulted in approximately 25% myrosases in the culture medium. The TGG1 recombinant protein was active in a wide pH and temperature range. The optimal reaction temperature was around 40℃, and the pH between 6-9. Myrosinase activity was activated by low concentrations of ascorbic acid, and suppressed by high concentrations. The apparent Km and Vmax were 65 μmol/L and 3.28 μmol ? min-1 ? mg-1, respectively when sinigrin was the substrate.