Isolation and Analysis of κ-Casein Glycomacropeptide from Goat Sweet Whey

• Published in: Journal of agricultural and food chemistry 2002-03, Vol.50 (7), p.2034-2038
• Main Authors: Silva-Hernandez, Eryck R, Nakano, Takuo, Ozimek, Lech
• Format: Article
• Language: English
• Subjects: Amino Acids - analysis; Animals; Biological and medical sciences; Caseins - analysis; Caseins - isolation & purification; Cattle; Chemical Fractionation; Chromatography - methods; Chromatography, Ion Exchange; Chymosin - pharmacology; Dimerization; Food industries; Fundamental and applied biological sciences. Psychology; Glycopeptides - analysis; Glycopeptides - isolation & purification; Goats; Milk - chemistry; Milk and cheese industries. Ice creams; Milk Proteins - chemistry; N-Acetylneuraminic Acid - analysis; Phenylalanine - analysis; Whey Proteins
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf010732q

Glycomacropeptide (GMP) was purified from goat sweet whey by anion-exchange and hydrophobic interaction chromatography. Approximately 0.06% (w/v) of sweet whey was recovered as GMP. Amino acid analysis of the GMP preparation showed that the content of phenylalanine (an amino acid that does not occur in goat GMP) was negligible, indicating that the GMP was of high purity. The goat GMP contained 25 μg sialic acid per mg of dry weight. This was approximately 3-fold lower than the sialic acid concentration in bovine GMP reported in the literature. Gel electrophoretic results demonstrated that most of the goat GMP occurs as a dimer. The GMP was intensely stained with Coomassie blue in 50% methanol containing 12.5% (w/v) trichloroacetic acid, but showed very weak metachromasia with the same dye in 45% methanol containing 10% acetic acid, a preparation commonly used to stain protein. Keywords: Anion-exchange chromatography; hydrophobic interaction chromatography; glycomacropeptide; purification; goat sweet whey