Study On Extraction Of5’-phosphodiesterase From Malt Root

This dissertation researched on preparing high purity and high biological activityof5’-phosphodiesterase （5’-PDE） from malt root. Put forward a new way for thecomprehensive utilization of malt root and realize sustainable development. Thisdissertation mainly studied the separation and purification process of5’-PDE from maltroot. The basic ingredients of malt root have been analyzed and pretreatment of maltroot. The extraction conditions were optimized.5’-PDE was purified throughmicrofiltration, ammonium sulphate precipitation and ultrafiltration. Freeze dryingtechnology was taken drying of5’-PDE. The main research contents and results are asfollows:The results show that malt root contains crude protein30.1%, crude fat1.7%,crude fiber15.8%, polysaccharide14.8%, water5.7%and ash6.6%.Higher extraction rate of5’-PDE was obtained through grinding granularity to100mesh. Optimal conditions for the extraction of5’-PDE from malt root were obtained byusing orthogonal assay design. The optimal conditions were as: pH=6, ratio of malt rootto water was1:10（w/w）, the extraction time was16h and temperature was4℃. Underthe condition, the total enzyme activity of5’-PDE was9361U.Mass of suspended matter, macromolecule other protein, inorganic salt and waterwere removed by microfiltration, ammonium sulphate（40%） precipitation andultrafiltration. After purification, the specific activity of5’-PDE reached to3018.9U/mg and the recovery rate of5’-PDE reached to80.8%. The membrane flux recoversto96%of the original flux through cleaning.5’-PDE was dried through freeze drying technology and the process parameterswere determined. The optimal conditions were as: the heating temperature was75℃,the vacuum was60Pa, the material thickness was8mm. Under the condition, the freezedrying efficiency reached to145.2g/h·m2, the specific activity of5’-PDE reached to3782.4U/mg with good solubility and the water content is less than3%.The molecular weight of5’-PDE was29.2kD through SDS-PAGE. The optimal pHand temperature are5and70℃, respectively. The5’-PDE was considerable stablewithin pH5⁷, and temperature50⁷0℃. Generally, Mg²⁺was an accelerant for5’-PDE, while Ca²⁺, Cu²⁺, Fe²⁺, Zn²⁺and Mn²⁺were inhibitors for it. The optimaltemperature for this5’-PDE was under-5℃.