Development of a New Method for the Absolute Quantification of Selenoproteins in Chicken Serum by Heteroatom-Tagged Proteomics

Selenium (Se) is an essential trace element for chickens that develops, through selenoproteins, important physiological functions. Although selenogen expression and Western blot analyses provided valuable information, there is a lack of information about the serum selenoproteome and quantitative data. In this work, we developed a new analytical method for the absolute quantification of selenoproteins and total selenometabolites in chicken serum using heteroatom-tagged proteomics, based on chromatographic separation and Se detection as a "tag" in an atomic detector. The approach was combined with bottom-up proteomics using liquid chromatography coupled to organic mass spectrometry after a tryptic digestion, and selenoprotein W was identified in chicken serum. Our results indicated that the majority of chicken serum Se is as selenoprotein P, followed by selenoprotein W, selenometabolites, glutathione peroxidase, and selenoalbumin. The approach could be a valuable tool to assess Se and selenoprotein status for the optimisation of supplementation strategies to meet the Se requirements of poultry.