Isolation and Characterization of a Novel Sialoglycopeptide Promoting Osteogenesis from Gadus morhua Eggs

eggs contain several nutrients, including polyunsaturated fatty acids, lecithin and glycoproteins. A novel sialoglycopeptide from the eggs of ( -SGPP) was extracted with 90% phenol and purified by Q Sepharose Fast Flow (QFF) ion exchange chromatography, followed by S-300 gel filtration chromatography. -SGPP contained 63.7% carbohydrate, 16.2% protein and 18.6% N-acetylneuraminic acid. High-performance size exclusion chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated that -SGPP is a 7000-Da pure sialoglycopeptide. β-elimination reaction suggested that -SGPP contained N-glycan units. Amino acid N-terminal sequence analysis indicated the presence of Ala-Ser-Asn-Gly-Thr-Gln-Ala-Pro amino acid sequence. Moreover, N-glycan was connected at the third Asn location of the peptide chain through GlcNAc. -SGPP was composed of D-mannose, D-glucuronic acid and D-galactose. Fourier transform-infrared spectroscopy (FT-IR), H-nuclear magnetic resonance spectroscopy ( H-NMR) and methylation analysis were performed to reveal the structure profile of -SGPP. In vitro results showed that the proliferation activity of MC3T3-E1 cells was significantly promoted by -SGPP. In vivo data revealed that -SGPP increased the calcium and phosphorus content of tibias and promoted longitudinal bone growth in adolescent rats.