A novel HPLC column switching method coupled to ICP-MS/QTOF for the first determination of selenoprotein P (SELENOP) in human breast milk.

In this work, we describe for the first time the presence of selenoprotein P in human breast milk. To this end, a novel analytical method has been developed based on a two-dimensional column switching system, which consisted of three size exclusion columns and one affinity column coupled to inductively coupled plasma mass spectrometry (ICP-MS). The method combines the accurate quantification of selenoproteins and selenometabolites by species unspecific isotopic dilution ICP-MS, with unequivocal identification by quadrupole-time-of-flight mass spectrometry. Several selenopeptides, which contain the amino acid selenocysteine (U, SeCys), were identified after tryptic digestion followed by their separation. The results reveal that the relative selenium concentration in colostrum follows the order: glutathione peroxidase (GPX) ≈ selenoprotein P (SELENOP) > selenocystamine (SeCA) > other selenometabolites (SeMB), in contrast with previously published papers (GPX > SeCA > selenocystine > selenomethionine). A mean concentration of 20.1 ± 1.0 ng Se g-1 as SELENOP (1.45 µg SELENOP/g) was determined in colostrum (31% of total selenium).

Biological interactions between mercury and selenium in distribution and detoxification processes in mice under controlled exposure. Effects on selenoprotein.

Antagonistic interactions between mercury (Hg) and selenium (Se), were evaluated in mouse (Mus musculus), as a mammalian model, in a series of controlled exposure experiments. The beneficial effect of Se against Hg toxicity involves a variety of biochemical and toxicological processes that have not been clarified yet. For this purpose, a metallomic workflow based on the use of size-exclusion chromatography (SEC) with inductively coupled plasma mass spectrometry (ICP-MS) detection was complemented with the speciation of selenoproteins and low molecular mass selenium species in serum and liver cytosolic extracts using a multidimensional approach based on SEC-AF-HPLC-ICPMS, using species-unspecific isotope dilution (SUID)-ICP-MS for selenium quantification. The results showed potential interactions between Hg/Se in organs and serum related to accumulation and detoxification processes, in addition to the effects of mercury on selenoproteins in hepatic cytosolic extracts and bloodstream when both elements are administrated at the same time. These results provide information about elements distribution, interactions and homeostasis and reveal the potential of metallomic approaches in exposure experiments.