The Purification And Properties Of Acid Phosphatase From Sweet Potato Leaves And Its Functional Groups

Acid phosphatase (Acid phospatase, referred to as the ACP) is in the phosphate monoester catalyzed hydrolysis of inorganic phosphate release water to explain enzyme in acidic environment. As important enzymes involved in the metabolism of phosphorus acid phosphatase-related, physiological and biochemical and growth of organisms play an important role. Currently, acid phosphatase has been used as an important indicator of certain diseases of prostate cancer, cervical cancer diagnosis. It plays an important role in the low phosphorus stress and breeding in plants.Sweet potato(Dioscorea esculenta) belongs to Convolvulaceae plant, if it is grown in the tropics,it is annual plant; if grown in the tropics.it is perennial. Sweet potato comes from South America, as a food crop,it is planted widely in China. It is China’s fourth largest food crop after rice, yield, wheat and maize.Sweet potato is yielded more than80%of the world. At present, the sweet potato is the main food crops into primarily for animal feed and industrial raw materials. Sweet potato is rich in starch and sugar, also contains rich protein. Sweet potato protein because of its unique nutritional value and physiological function, is currently being widely studied. With the sweet potato widely used in the field of food processing, it will greatly promote the sweet potato production and processing. The results are as follows:1. Isolation and purification of sweet potato acid phosphataseElectrophoresis-pure Acid phosphatase(ACP) from sweet potato old leaves was obtained from a series of procedures, which included homogenization, extraction, Ammonium sulfate fractional precipitation, DEAE-Sepharose chromatography and Superdex-200gel filtration, then we identified it with SDS-PAGE. In this process, the purification fold was169.07, the specific activity of it reached251.49U/mg and3.5%of the ACP activity was recovered. 2. Properties of acid phosphatase from sweet potatoThe result showed that the enzyme was a single subunit protease. The relative molecular weight of this ACP was42.3kD, and the weight of subunit was41.2kD. The optimum temperature and pH of the enzyme were65℃and5.2. This ACP could be stable below40℃and in the pH ranged from4.0to6.0. Its Michaelis-Menten Kinetics (Km) towards pNPP was0.258mmol/L. The enzyme activity could be obviously inhibited by methanol, EDTA and Oxalic acid. Hg2+and Ag+could strongly inhibited its activity.3. Chemical modification of acid phosphatase from sweet potatoThe modification results showed that:Sulfydryl, Tryptophan and sulfur ether methionine residues the composition of the indispensable groups of active center, Tyr,Lys,Ser and disulfide bonds may residue the spatial conformation of the enzyme.