Abstract: In this paper, the isolation and purification conditions for CGMP from pepsin casein hydrolysate were studied by ammonium sulfate precipitation, dialysis desalting and Q Sepharose fast flow chromatography. The results show that 0.71% recovery rate CGMP with high purity could be obtained immediately from salting-out supernate by 60% saturation degree ammonium sulfate precipitation;and non-CGMP proteins could be separated with 20% saturation degree ammonium sulfate effectively;Desalting fraction of crude separating mixture could be chromatographed by Q Sepharose FF equilibrated and added samples with pH 8.5, 20mM Tris buffer and eluted with 20mM Tris buffer, pH 7.1containing 0.3M NaCl; and the maximal bearing capacity was 34.2mg protein for 1ml resin. With that optimizing purification conditions, the estimated yield of CGMP fraction was approximately 2.19% of casein; its sialic acid recovery rate to entire content in hydrolysate supernatant was 87.4% and glycosylation ratio of purified CGMP could be raised to over 0.472. The entire processing condition was simple, fast ,low cost and suitable for industry.

Key words: casein glycomacropeptide (CGMP), pepsin, salting-out, ion-exchange chromatography, sialic acid