Studies On Isolation, Purification Of Sweet Potato Glycoprotein (Ipomaea Batatas LAM) And Elucidation Of Its Sugar Chain Structure

Having exploited Beijing No.2 sweet potato (Ipomoea Batatas LAM) as material in this dissertation and utilizing a series of modern technologies such as isolation and purification technology, instrument analysis technology, the author has systematically studied the physicochemical properties of sweet potato glycoprotein (SPG) and its sugar chain (SPG-l-P) structure. The results indicated :(1) Four grades of sweet potato glycoprotein SPG-1, SPG-2, SPG-3, SPG-4 were isolated and purified from Beijing No.2 sweet potato through modern isolation and purification technology. Their ratios were 1. 23, 0.03, 0.14, 0. 05% respectively. By means of Sepharose CL-6B, ConA-Sepharose and HPLC, each grade was sole peak. The molecular weight of SPG-1, SPG-2, SPG-3 and SPG-4 was 49.97, 28.36, 10.68, 8.25+104 respectively by Sepharose G-100 determination and by HPLC, their molecular weights were 50.83, 29.06, 11.19, 8.60+104 respectively. The four grades of sweet potato glycoprotein were neutral glycoconjugates containing no starch, no reduction sugar and no polyphenol rather than protein. The total sugar content of SPG-1, SPG-2, SPG-3, SPG-4 was 97.32, 92.54, 76.65, 99.14% respectively and their contents of protein was 2.15, 6.83 , 22.36, 0.43% respectively. All of the four grades were O- glycoprotein.(2) Sugar chain SPG-l-P was obtained from SPG-1 by means of B-elimination reaction release and modern isolation and purification, which presented single symmetrical peak in Sepharose CL-6B column and capillary electrophoresis,. And the molecular weight of SPG-l-P determined by Sephadex G-100 and by HPLC was 40.67, 39.24 +104 respectively.(3) Employing chemical methods and instrument analysis technology, the author obtained the possible primary structure of SPG-1-P as follows:The higher structure of SPG-l-P was mainly composed of sugar (C6H12O6) crystal and contained some non-crystal. The crystal system of SPG-l-P was monoclinic unit cell. Each crystal cell was composed of 8 glucoses and it's crystal cell parameters were a=0.664nm, b=1.2nm, c=1.97nm. Aqueous solution of SPG-l-P had an apparently positive Cotton effect at 20 C .This dissertation possesses the following innovations :1.Initially utilizing sweet potato as material, taking developing the third generation healthy food as objective, applying the isolation and purification technology of modern bioactive substances, the author successfully obtained pure SPG from sweet potato. In addition, its colour reaction, molecular weight, purity, characteristics of glycopeptide linkage, the contents of total sugar and protein and amino acid composition etc., were studied systematically.2.The author employed B-elimination reaction and purification technology of active polysaccharide to release sugar chain from SPG successfully and obtain pure sugar chain, moreover, its purity and molecular weight were determined. Adopting complete acid hydration and methylation, Smith decomposition, GC, IR, GC-MS, NMR etc., the author studied the primary structure of sugar chain in SPG-1 and initially produced the possible linkage of repeated units in its chemical structure as well as probed into the higher structure of sugar chain by means of X-ray fiber diffraction and CD spectrum.