Separation and Purification of Sialylglycopeptide from Egg Yolk Based on Cotton Hydrophilic Chromatography

The peptide portion of the sialylglycopeptide (SGP) in egg yolk is composed of six amino acids (KVANKT), among which asparagine (N) is modified by a complex sialylated N -glycan. Sialylglycopeptides are mainly obtained from egg yolk through a cumbersome, expensive, and poorly scalable process. In this study, a simple and low-cost method for the separation and purification of sialylglycopeptide from egg yolk was developed based on hydrophilic interaction chromatography with medical absorbent cotton as stationary phase. Fifty egg yolks were treated with phenol to obtain the crude sialylglycopeptide. The latter was then formulated into a 150 mg/mL solution and loaded on a cotton hydrophilic chromatographic column, followed by treatment with 100%, 95%, 85% and 75% acetonitrile (ACN) aqueous solution to remove impurities. Finally, deionized water was applied for the final elution step. By this way, 300 mg of sialylglycopeptide was yielded and its purity was determined by high-performance liquid chromatography to be 95%. The glycan composition and glycosylation site of the sialylglycopeptide were validated by electrospray ionization mass spectrometry and tandem mass spectrometry.