Purification of Glycomacropeptide from Caseinate Hydrolysate by Gel Chromatography and Treatment with Acidic Solution

ABSTRACT: Glycomacropeptide (GMP) was purified from chymosin-hydrolyzed caseinate solution by the procedure involving: (1) gel chromatography on Sephacryl S-200 at pH 7.0 to obtain a crude GMP fraction; (2) addition of acidic solution, pH 3.5 to the crude glycomacropeptide to precipitate contaminating protein and/or peptide; and (3) re-chromatography of the material soluble in the acidic solution on Sephacryl S-200 at pH 3.5. The purified GMP accounted for 5.3% of dry weight of caseinate hydrolysate, and 0.7% of dry weight of sodium caseinate powder. The preparation was of considerably high purity with its amino-acid composition showing only traces (each < 1 residue / peptide) of arginine, histidine, phenylalanine, and tyrosine, the amino acids that do not occur in GMP.