Abstract: In order to systematically elucidate the structural and functional characteristics of phosphorylated proteins in egg white, the phosphoproteome in chicken egg white (CEW) was identified and analyzed with a proteomic strategy in this study. Chicken egg white was digested with trypsin, and phosphopeptides were enriched from the resulting hydrolysate by using immobilized metal-chelate affinity chromatography, and then identified by nano-liquid chromatography/tandem mass spectrometry. After searching against the protein databases, a total of 33 unique phosphorylated peptides were identified, including 41 phosphorylated sites, belonging to 25 egg white phosphorylated proteins. The motif analysis showed that “S-X-E” was the most over-represented. The results of gene ontology annotation and classification indicated that the identified phosphoproteins in chicken egg white were mainly involved in the processes of “biological regulation”, “stimulation reaction” and “development”, and associated with the functions of “binding” and “catalysis”. These results provide key structural information of phosphorylation modification of egg white proteins for future relevant research.

Key words: chicken egg white, proteins, phosphoproteome, gene ontology analysis, ovalbumin