Selenium
Its Molecular Biology and Role in Human Health
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Beschreibung
Selenium is an essential trace element in the diet of humans and many other life forms. As discussed in this book, selenium plays an important role in preventing certain forms of cancer, heart disease and other cardiovascular and muscle disorders. Evidence points to numerous other health benefits including an indispensable function in development, male reproduction and the immune system. In addition, selenium serves as an antiviral agent and may delay the onset of AIDS in HIV positive patients and delay the aging process. This element occurs primarily in cellular proteins in the form of a novel amino acid selenocysteine. Selenocysteine is the 21st amino acid in the genetic code and is cotranslationally incorporated into protein in response to the codon, UGA. Selenoproteins control redox homeostasis and are involved in variety of cellular pathways. The emphasis of this book is on the current status of the molecular biology of selenium. The importance of this element in human health is also highlighted.
The discovery of selenoproteins in 1973 was the starting point for today's flourishing selenium field [1,2]. It provided evidence that selenium had biochemical functions that could account for its nutritional effects [3,4]. Further, it opened the selenium field to investigation by the methods of biochemistry, which led to the identification of several more selenoproteins and showed that selenocysteine was the form of the element in animal selenoproteins and in most bacterial ones. Although noteworthy efforts were made to uncover the mechanism of selenocysteine and selenoprotein synthesis using biochemical methods, the problem yielded only when attacked with the methods of molecular biology [5,6]. The bacterial mechanism was characterized first; characterization of the animal mechanism is a work in progress. It is interesting to note that the only genes that are devoted to selenium metabolism are those that support selenoprotein synthesis and selenocysteine catabolism. Consequently, it seems likely that competition for selenium between selenoprotein synthesis and the production of selenium excretory metabolites [7] controls who- body selenium homeostasis. The physiological functions of selenium derive fi-om the catalytic and physical properties of selenoproteins. Selenoproteins such as the glutathione peroxidases and the thioredoxin reductases have redox activities that allow them to serve in oxidant defense. The deiodinases use their redox activities to activate and inactivate thyroid hormones. From these two examples, it can be seen that selenoprotein functions are diverse while having in common a redox mechanism.
Features the many new discoveries have occurred since the 1st edition on Selenium was published in 2001 New investigators who have made important contributions to the field have been added as chapter authors Includes supplementary material: sn.pub/extras
Autor*in
Dolph L. Hatfield
Themen in »Selenium«
AIDS Diabetes Evolution HIV Proteomics RNA Regulation biosynthesis cancer genes metabolism molecular biology prokaryotes proteins tRNA