Preparation Of The Secoisolariciresinol By Enzyme

Secoisolariciresinol （SECO）is the most essential ingredient of lignans, which is one ofthe phytoestrogens. SECO has strong antioxidants. It has been proposed to play a role in theprevention of cancer, atherosclerosis and diabetes.Preparation of the SECO by enzyme was mainly studied in this paper. SDG-glucosidasethat hydrolyzes the glucopyranoside bond of secoisolariciresinol diglucoside（SDG） to releaseSECO was isolated from Asp.oryzae39strain which was selected from different fungus. Thestrain grew in30℃.SDG-glucosidase was purified by DEAE-cellulose column and PAGE. The pure enzymewas purified to one spot in SDS-PAGE, and its molecular weight was about64.9kDa. Theoptimum temperature of the SDG-glucosidase was40℃, and the optimum pH was5.0. TheSDG-glucosidase was stable at less than65℃, and pH4.0-6.0. Na⁺, K⁺, Mg²⁺and Ca²⁺ionshave no significant effect on enzyme activity, Zn²⁺and Cu²⁺ions have weakly effect onenzyme activity, but Fe³⁺ion inhibits enzyme activity strongly. The Km value ofSDG-glucosidase was0.145mmol/L·h and the Vmax value was0.66mmol/L.The optimum concentration of SDG was30mg/mL, and reacted about8hours. Themethod of extraction was used to isolate and purify the SECO, and determined by HPLC: theSECO was contented about60%, and the yield of SECO was about90%.