Study On Extraction, Purification And Enzymology Character Of Beta Amylase From Sweet Potato

Beta amylase mainly exists in plants and microorganism, exist heat resistance bad and extraction cost is higher from extraction beta amylase of microorganism, but the enzyme activity is high, heat resistance good, a wider range pH and the production technology is simple, mature, low cost. In China, Sweet Potato'planting is wilder and low price, it is suitable to extract beta amylase for the raw material, but Sweet Potato are mainly used to produce silk noodles and starch, other purposes is few. Sweet Potato starch'production will produce large quantities of waste water, contains a lot of organic substances, such as beta amylase, if we could extract the beta amylase from the waste water, not only can resolve the pollution, but also can create great economic benefits, and have great theoretical significance and practical value. This paper researched the extraction, purification, identification and enzymologist character from the beta amylase of Sweet Potato. The main research results were as follows:Use water extraction beta amylase of Sweet Potato under different conditions, the results indicated, in pH 5.5 phosphate buffers, liquid to material ratio 2:1, the extraction effect is best and the enzyme activity is 122336U/g. Through to the Sweet Potato habitat, texture, placing time contrast that under the Shanxi white heart of Sweet Potato storied for 30 days condition, the activity of beta amylase is highest and the relative enzyme activity is 129%.Through to comparison ammonium sulfate and organic solvent precipitate beta amylase of Sweet Potato, it was concluded when the acetone volume ratio is 3:1, pH is 4.5 to 5.0, the recovery coefficient reached 90.7%, and the specific activity increased 3.29-fold relative to the crude enzyme solution. Meanwhile, with the ultra filtration experiment to beta amylase of Sweet Potato, it was concluded that when the operating pressure is 0.14Mpa, the temperature is 20℃, the operating time is 40 minutes and liquid pH is 7.0, the ultra filtration flux is the best. With DEAE column chromatography purification to beta amylase of Sweet Potato, the purification is better, the recovery coefficient reached 18.5%, and the specific activity increased 14.6-fold relative to the crude enzyme solution.Identified the amylase after purification of adopting polyacrylamide gel electrophoresis, the result is a tape with clear and the molecular weight is basic same with the mark about 55000 Kda. Using high performance liquid chromatography analyzing the breakdown products after purification of beta amylase in the conditions of column temperature is 30℃, acetonitrile to water volume ratio is 3:1, flowing rate is 1.5ml/min, feeding sample volume is 10μl, the results show that the breakdown products are basic malt sugar.Studied the enzymologist characters, include the optimum temperature, temperature stability, optimal pH, pH stability, metal ion interaction after purification, results show that the optimum temperature is 50℃, the temperature is stability between 30 to 50℃, the optimal pH is 5.0,and the pH stability is good between 3.0 to 6.0 of beta amylase action, Mn²⁺ has great activation function to beta amylase, Mg²⁺, Na⁺, K⁺ have faint function, and Fe³⁺,Cu²⁺,Zn²⁺ have strong inhibition, and Ca²⁺ has no effection to beta amylase.Preserve beta amylase of sweet potato after column chromatography of DEAE, the results show that the loss rate range of enzyme activity is between 31% to 67% after drying, and freeze-drying is between 2% to 6%.