Purification and characterization of dioxygenase from Schwanniomyces occidentalis to biodegrade β-carotene

The purification and enzymological characteristics of dioxygenase were studied and the enzyme was used to digest the β- carotene to produce flavor materials.The dioxygenase was produced by liquid fermentation,ammonium sulphate precipitation,membrane dialysis,DEAE-Sepharose fast flow ion exchange chromatography and gel filtration chromatography( G-100).The results were concluded that the purity of the dioxygenase produced by Schwanniomyces occidentalis was increased for 36.43 times,the recovery of the enzymatic activity was 21% and its molecular mass was 55.0 ku. The optimal temperature and p H for the purified dioxygenase were 40℃ and 8.5repectively.The effect of metal ions on dioxygenase activity was with the following order: Fe²⁺> Mg²⁺> K⁺> Na⁺>Mn²⁺> Cu²⁺> Ca²⁺> Zn²⁺> Ag⁺.Fe²⁺and Mg²⁺had a strongpositive effect on the enzyme,however Zn²⁺and Ag⁺ had a negative influence on the enzyme. The purified dioxygenase was inhibited by SDS and pepstatin. Dynamic studies demonstrated that the Kmand V_max of the enzyme was 8.24 × 10^-4mol / L and 2.16 × 10^-4mol /( min·mg)respectively.