Detection of Sialylated Phosphorylated κ-Casein Glycomacropeptide Electrophoresed on Polyacrylamide Gels and Cellulose Acetate Strips by the Thiobarbituric Acid and Malachite Green Dye Reactions

• Published in: Journal of agricultural and food chemistry Vol. 55; no. 7; pp. 2714 - 2726
• Main Authors: Nakano, Takuo, Ikawa, Noriaki, Ozimek, Lech
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 04.04.2007
• Subjects: analytical methods; Animals; Biological and medical sciences; caseinomacropeptide; Caseins - analysis; Caseins - chemistry; Cattle; chemical composition; detection; Electrophoresis, Polyacrylamide Gel; food analysis; Food industries; Fundamental and applied biological sciences. Psychology; General aspects; glycomacropeptide; Glycopeptides - analysis; Glycopeptides - chemistry; Glycopeptides - isolation & purification; kappa-casein; margarine; Methods of analysis, processing and quality control, regulation, standards; Milk - chemistry; Milk and cheese industries. Ice creams; N-Acetylneuraminic Acid - analysis; peptides; Phosphorus - analysis; Phosphorylation; sialic acids; whey; Sialic acid; κ-casein glycomacropeptide; Edible fat; Dairy product; Caseinomacropeptide; Phosphorus; Whey; Milk protein; Analysis method; Casein; Electrophoresis; Control method; Margarine; Cellulose acetate; Detection; Acid dye; Green
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf062987f

A 64 amino acid residue sialylated phosphorylated glycomacropeptide (GMP) from bovine sweet whey can be detected as a Coomassie blue-staining peptide by electrophoresis on sodium dodecyl sulfate (SDS)−polyacrylamide gels. There is, however, limited information available concerning detection of GMP as a sialylated phosphorylated compound. Samples of GMP were electrophoresed on SDS−polyacrylamide gels or cellulose acetate strips (CAS). Immediately following electrophoresis, fractions obtained by cutting gels or strips were subjected to sialic acid determination by the thiobarbituric acid reaction and phosphorus determination by the malachite green dye reaction. Both determinations were found to be sensitive enough to detect approximately 20 and 40 μg of GMP in CAS and SDS gels, respectively. Further studies demonstrated that sialylated phosphorylated GMP can be detected on either SDS gels or CAS loaded with whey products or whey-added margarine residues. Keywords: Caseinomacropeptide; κ-casein glycomacropeptide; electrophoresis; sialic acid; whey; phosphorus; margarine