Studies On Sweet Potato Glycoprotein And Its Antilipemic Function

The paper studied on the isolation, purification and structure determination of Sweet Photato Glycoprotein (SPG) from a cultivar - Beijing 2,as well as its antilipemic function, mechanisms. The results indicated:The purified SPG is a kind of white powder, output of which is at 0.25 percent by fresh weight. It is dense in water, and it is not dissolved in high organ-solvents such as alcohol and acetone. Under the concentration of SPG at 1.02g/ml,the pH is about 5.6,degree of opticity +46,glutinosity 2.95mpa.s, ultra-violet absorption 280nm.The molecular weight of SPG was 62 000Da. The protein content was up to 10.71%,and its polysaccharide content was 80.06%.Serum TC and TG contents of hyperlipidemia rats significantly decreased when SPG is used between 5mg/kg.d and 15mg/kg.d by intreperitional injection, especially TC content as compared with control (P<0.01).The effects of it lied in increment of HDL-C and reduction of LDL-C. Meanwhile, SPG evidently inhibited the cholesterol content of liver as compared with control (P<0.05).The reduction rate of TC in hyperlipidemia rats increased with SPG dose increasing at 0~200mg/kg.d by oral, then decreased after dose of more than 200mg/kg.d.The mechanisms of antihyperlipemic function mainly included enhancing LCAT activity, increasing carbohydrate allogenous rate, and keeping SPG's molecularstructure integral.SPG could significantly lower AI and cholesterol contents in serum or liver at different diet levels. Among food-processing factors, temperature and oxidant (HIO4) had the most serious effects on antihyperlipemic funtion of SPG. Within a particular range of 60-70 of temperature or 3.5-7.5 of pH, the antihyperlipemic function of SPG remained stable. Out of this range, activity would decrease.Although the active-position located in polysaccharide part,by comparing the antihyperlipemic function of SPG with its polysaccharide part, the results suggested that the protein part played exaggerating and intensifying role on antilipemic function of SPG.