Selenium is an essential element for life but toxic at levels little above those required for health. In the last years it has been revealed that selenium has a large number of biological functions in humans. The most important and known selenium property is the antioxidant action (anticarcinogenic) because it forms selenocysteine, part of the active center of the glutathione peroxidase (GPx) enzyme. Therefore, knowledge regarding the speciation of selenium in the human body rather than total selenium content is necessary for a better understanding of its status. In mammals, including man, about 30 selenoproteins have been reported so far but only a few of them, namely GPx, type-1 iodothyronine 5'-deiodinase and selenoprotein P (SelP), have been identified and comprehensively characterized. Hence, the search for new Se-containing proteins and the study of their characteristics and biological functions is still undergoing. The main selenoproteins in human blood (serum) are SelP, GPx and selenoalbumin (where Se is not present in an active form, and hence it is considered a Se-containing protein). Speciation analysis of these selenoproteins is difficult, because of their low concentration and the high amounts of some other non-selenium proteins, which interfere in the liquid chromatographic separation (HPLC). This study aims at the development of a new analytical approach for speciation analysis of selenoproteins (SelP, GPx and albumin) at trace and ultra-trace levels and its application to the analysis of human samples, particularly blood serum. For this purpose, various separation techniques, including size-exclusion, anion exchange, reverse-phase and affinity liquid chromatography hyphenated to inductively coupled plasma-(quadrupole) mass spectrometry (ICP-MS) are investigated. Quantification of selenoprotein species is carried out by post-column (online) isotope dilution-ICP-MS, using enriched 77Se. The confirmation of the species identity is carried out by electrospray ionization-mass spectrometry (ESI-MS) and Matrix-Assisted Laser Desorption/Ionization-Mass Spectrometry (MALDI-MS). Finally, information regarding the distribution of selenium in serum proteins from healthy and unhealthy subjects is addressed.
SPECIATION ANALYSIS OF SELENOPROTEINS IN HUMAN BLOOD
G Cozzi;W Cairns;P Cescon;C Barbante
2007
Abstract
Selenium is an essential element for life but toxic at levels little above those required for health. In the last years it has been revealed that selenium has a large number of biological functions in humans. The most important and known selenium property is the antioxidant action (anticarcinogenic) because it forms selenocysteine, part of the active center of the glutathione peroxidase (GPx) enzyme. Therefore, knowledge regarding the speciation of selenium in the human body rather than total selenium content is necessary for a better understanding of its status. In mammals, including man, about 30 selenoproteins have been reported so far but only a few of them, namely GPx, type-1 iodothyronine 5'-deiodinase and selenoprotein P (SelP), have been identified and comprehensively characterized. Hence, the search for new Se-containing proteins and the study of their characteristics and biological functions is still undergoing. The main selenoproteins in human blood (serum) are SelP, GPx and selenoalbumin (where Se is not present in an active form, and hence it is considered a Se-containing protein). Speciation analysis of these selenoproteins is difficult, because of their low concentration and the high amounts of some other non-selenium proteins, which interfere in the liquid chromatographic separation (HPLC). This study aims at the development of a new analytical approach for speciation analysis of selenoproteins (SelP, GPx and albumin) at trace and ultra-trace levels and its application to the analysis of human samples, particularly blood serum. For this purpose, various separation techniques, including size-exclusion, anion exchange, reverse-phase and affinity liquid chromatography hyphenated to inductively coupled plasma-(quadrupole) mass spectrometry (ICP-MS) are investigated. Quantification of selenoprotein species is carried out by post-column (online) isotope dilution-ICP-MS, using enriched 77Se. The confirmation of the species identity is carried out by electrospray ionization-mass spectrometry (ESI-MS) and Matrix-Assisted Laser Desorption/Ionization-Mass Spectrometry (MALDI-MS). Finally, information regarding the distribution of selenium in serum proteins from healthy and unhealthy subjects is addressed.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
