Studies On Isolation Purification And Identification From Sweet Potato Glycoprotein

Sweet potato was used as raw material in this dissertation. With a series of moderntechnologies, including isolation and purification technology, instrument analysistechnology, the author has systematically studied the isolation, purification andphysico-chemical properties of sweet potato glycoprotein (SPG) and its structure.The optimum extraction process and conditions of sweet potato water-solubleglycoprotein (SPWSGP) were chosen by considering the effect of each factor andsubsequently doing orthogonal experiment: grinding degree is 80 mesh, the ratio of rawmaterial to water is 1:15, extracting time is 3 hours and extracting times is 1. The bettercondition of removing protein is determined by the single-factor experiment: the ratio ofsample liquid to Sevage liquid is 2, the ratio of chloroform to 1-butanol is 2, removingprotein times is 3, the time of removing protein is 20 minutes. By comparison, gradientelution with NaHCO3 is the better elution condition of DEAE-Cellulose52 ion exchange.The collected liquid is further purified by dialysis, concentration and Sephadex G100 gel.Then purified SPWSGP was obtained.The physico-chemical properties of SPWSG were investigated. The white flocculentglycoprotein was soluble in water but insoluble in organic solvents such as ethanol andacetone. The results of HPLC and SDS-PAGE had shown the purity of SPWSGP wasabout 97%. The molecular weight of the SPWSGP is measured with two methods, i.e.HPLC and SDS-gel electrophoresis, they being 125,750 and 58,575 respectively. Thethermodynamic properties of SPWSG and deglycosylated SPWSG was also studiedrespectively by DSC. The result showed that the temperature of denature for the formeris 106.67°C, while that for the latter is 66.84°C. These results showed that theoligosaccharide chain of SPWSG played a role of strengthening resistance todenaturation.The content of protein in SPWSG is 61.2% using Lowry method. The neutral andacidic monosaccharide is 38.7% through colorimetric method. There are 5 kinds ofmonosaccharide in SPWSGP, they are as follows : Arabinose, Xylose, Mannose, Glucoseand Galactose. Among them, Galactose occupies about 60.3%. SPWSGP contains manykinds of essential amino acids, among which the contents of Asp, Glu, Arg, Cys, Phe,Leu are higher. The structure of SPWSGP was studied by IR and alkaline β-eliminationreaction. SPWSG contains α-glucosidic bonds;furthermore the type of the glucosidicbonds was pyranose;protein was covalently linked with carbohydrate by O-glycosyllinkage.