Comparative proteomic analysis of egg white proteins during the rapid embryonic growth period by combinatorial peptide ligand libraries

Egg white proteins provide essential nutrients and antimicrobial protection during embryonic development. Although various biological functions of major egg white proteins have been investigated via embryogenesis, understanding of global changes in low-abundance proteins has been limited. In the current study, a proteomic analysis of low-abundance egg white proteins was conducted using combinatorial peptide ligand libraries (CPLL), two-dimensional gel electrophoresis (2-DE), and matrix-assisted laser desorption/ionization-time-of-flight with two mass analyzers for tandem mass spectrometry (MALDI-TOF MS/MS) during the rapid embryonic growth period. Significant increases in the relative abundance of 88 protein spots (P <= 0.05), of which 47 spots were found to correspond to 10 proteins from 8 protein families were identified over 16 d incubation. During this developmental process, the protein concentration increased and the amount of albumin solid material decreased in the residual egg white. Clusterin precursors were observed over a wide range of pH values and the tenp protein increased continuously during embryonic development. Low-abundance proteins were identified in a comparison of optimal incubation conditions to the altered conditions of 2 control groups to better understand the function of these proteins in egg whites. Collectively, these findings provide insight into the supportive role of the egg white during embryonic development, enabling a broader understanding of chick embryogenesis.