Preparation and characterization of phosphopeptides from egg yolk phosvitin

Egg yolk phosvitin is a highly phosphorylated protein. Its derived phosphopeptides may help improve bone and dental health, in addition to its antioxidant and anti-inflammatory activities. However, the structural information of these peptides was poorly characterized. In this study, we aimed to prepare phosvitin phosphopeptides by enzymatic hydrolysis and characterize the peptide sequences and phosphorylation by LC-MS/MS. Phosvitin was partially dephosphorylated by 0.2 M NaOH prior to pancreatin hydrolysis. The degree of hydrolysis was 12.9% and the peptide recovery was 6.1% (based on egg yolk). The N/P value of 3.9 was comparable or lower than purified casein phosphopeptides, which ranged from 6 to 18. After anion exchange chromatography, 32 peptides were identified from three phosvitin domains: AEFGTEPDAKTSSSSSSASSTATSSSSSSASSPN (PV 1-34), KPMDEEENDQV (PV 37-47) and SGHLEDDSSSSSSSSVLSKIWG (PV 190-211). These peptides contain up to 10 phosphate groups.