Study On The Separation And Purification Of Glycomacropeptide Derived From Milk

Casein glycomacropeptide(CGMP)is a highly biologically active whey protein with superior purity. It is one of the important minor proteins present in whey along with lactoperoxidase, lactoferrin and protease peptones. The glycomacropeptides acts as a biological peptide, which has several nutritional and medical functions. Preparation of glycomacropeptides in the laboratory is usually carried out by chymosin digestion of pure κ-CN and removal of para-κ-CN from sodium caseinate. Glycomacropeptides have been isolated from chymosin-hydrolyzed caseitate by ultrafiltration and ion-exchange chromatography. There is, however, limited information available on the preparation of this glycopeptide by gel chromatography. Cheese whey is considered to be the most suitable source of glycomacropeptides for industrial purposes, but its high lactose, protein and ash content makes it technically difficult to isolate glycomacropeptides on a large scale. On the basis of the thermo-resistance of glycomacropeptides and the differences in molecular weight of its polymeric and monomeric forms, we have modified a developed method of isolating glycomacropeptides for the purposes of large-scale industrial production, in order to make it straightforward and maintaining a high yield and purity in the glycomacropeptides fraction. The research separated and prepared CGMP by ultrafiltration from commercial whey powder. The optimum parameter including ultrafiltration temperature, time, pressure was obtained. The research purified CGMP mixture by Sephadex G-100. The information about purifying CGMP by gel-chromatogram was limited. The result indicated that it got obvious purifying result to separate CGMP by selecting appropriate column size, eluent, velocity of flow. Quantitative and qualitative analysis by gel-gelation and amino acid analysis indicated that the average molecular of CGMP was 31637, approximately to 32000 which was reported accounting for 22.35%of whey protein and ultrafiltration could obtein CGMP, accouting for 58.91% of whole protein, which is 2.6 higher than whey powder. Sephadex G-100 also had limited application,such as the production was not pure,but of mixed protein/peptide. The reason maybe their molecular weight and spatial structure were similar to CGMP which resulted in gel-chromatogram and electrophoresis not separating them, but gel-scanning software considered them pure. These results clued on us that multi-methods could enhance veracity when forecasting molecular weight and concentration of a protein.