Study On Purification And Enzymatic Properties Of Dextranase

Dextranase is a hydrolytic enzyme, which is highly specific in the way it hydrolyzes α-1,6-glycosidic bonds; And the condition for efficient catalytic hydrolysis of dextran is mild. For the sugarcane industry, long-term post-harvest stack and poor sanitation may result in the microorganism infection of sugarcane, and thus generates a large amount of dextran. Dextran will consequently interfere with the process that followed:reduces the sucrose productivity and the product quality. Since Dextranase is an important means to solve a series of problems caused by dextran, it would be important to study on fermentation production, extraction, purification, enzymatic properties and preservation methods.This paper studies the separation and purification of Dextranase, which is constitutive expressed by Pichia Yeast. The preliminary separation makes use of selective precipitation and ultrafiltration. Then, it would establish a group of efficient process parameters for the aqueous two-phase extraction, by using different types of salt, polymers of different molecular weight, and by changing pH.In PEG4000-(NH4)2SO4two-phase system, the rates of extraction and enzyme solution yield are more than95%, when polyethylene glycol and ammonium sulfate concentration is at13%. The following studies indicate that the optimal conditions for enzymatic reaction are45℃, pH5.5and substrate concentration of20mg/mL. Reaction of Enzyme is inhibited by Fe3+and Cu2+, while catalytzed by Mn2+and Fe2+. As for storage, the intolerance ambient temperature for enzyme is above30℃; it remains stable when the pH is between5.0and5.8and the temperature is at4℃. When stored with additional30%of glycerol at room temperature, the active rate of enzyme remains over80%in5weeks.