摘要
The cuticle is the outermost layer of the avian eggshell, whose protein constituents remain virtually unknown. We hypothesize that cuticle components play a major role in microbial resistance, since eggs with incomplete or absent cuticle are more susceptible to bacterial contamination. In this study we extracted proteins from the outermost non-calcified layer of the cuticle of chicken eggs and subjected them to LC/MS/MS proteomic analysis. We identified 47 cuticle proteins with high confidence and reproducibility. Two proteins, similar to Kunitz-like protease inhibitor and ovocalyxin-32 (a carboxypeptidase A inhibitor), were the most abundant of the cuticle proteins. A number of proteins known to have antimicrobial activity in the egg were detected (lysozyme C, ovotransferrin, ovocalyxin-32, cystatin, ovoinhibitor) as well as possible new candidates (myeloperoxidase, ovocalyxin-36 and members of the SERPIN family). This is the first comprehensive report of cuticle proteome, a starting point to determine cuticle function and the molecular basis of its antimicrobial properties.