2015/05/21

Human Basal Tear Peptidome Characterization by CID, HCD, and ETD Followed by in Silico and in Vitro Analyses for Antimicrobial Peptide Identification.

Endogenous peptides are valuable targets in the analysis of biological processes. The tear film contains proteins and peptides released by the tear duct mucosal cells, including antimicrobial peptides involved in the protection against exogenous pathogens; however, the peptide content (peptidome) of the tear liquid remains poorly characterized.

The proteomics platform at CIC bioGUNE, in collaboration with the neighbor biotechnology company Bioftalmik SL and researchers from Pontificia Universidad Católica in Valparaiso (Chile) have conducted a study to decipher the tear film peptidome.

For that, specific mass spectrometry methods were used such as CID, ETD, and HCD, for the characterization of the tear peptide content. Altogether, 234 different peptides were identified, leading to the generation of the largest data set of endogenous tear peptides to date. The antimicrobial activity prediction analysis performed in silico revealed different putative antimicrobial peptides. Two of the extracellular glycoprotein lacritin peptides were de novo synthesized, and their antimicrobial activity against common eye pathogenic Gram-positive and Gram-negative bacteria was confirmed in vitro.

The findings presented in this study demonstrate the benefits of using different peptide fragmentation methods in mass spectrometry for the analysis of endogenous peptides. Moreover this strategy provides a useful approach for the discovery of peptides with antimicrobial activity. Moreover, the same workflow could be used for the identification and discovery of endogenous peptides with other interesting biological functions such as cytoprotection, anti-inflammation or wound healing, widening the available array of applications.

This study was recently published in "Journal of Proteome Research": Azkargorta M, Soria J, Ojeda C, Guzmán F, Acera A, Iloro I, Suárez T and Elortza F.

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