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Selenium Proteins Containing Selenocysteine

  1. William T. Self

Published Online: 15 SEP 2012

DOI: 10.1002/9781119951438.eibc0199.pub2

Encyclopedia of Inorganic and Bioinorganic Chemistry

Encyclopedia of Inorganic and Bioinorganic Chemistry

How to Cite

Self, W. T. 2012. Selenium Proteins Containing Selenocysteine . Encyclopedia of Inorganic and Bioinorganic Chemistry. .

Author Information

  1. University of Central Florida, Orlando, FL, USA

Publication History

  1. Published Online: 15 SEP 2012


Selenium is incorporated in the form of the nonstandard amino acid selenocysteine into selected proteins of organisms belonging to all three lines of descent. The majority of these proteins, which contain selenocysteine in the active site, catalyze oxidation–reduction reactions and are involved in numerous biochemical and regulatory processes, which in many cases are indispensable for the organism. Because of significant differences in the chemical reactivity of selenocysteine in comparison to cysteine, selenoenzymes display a greatly increased rate of catalysis and, in some cases, have an extended substrate specificity. Apart from its biochemical function, selenocysteine is also unique since its incorporation is DNA-encoded and its cotranslational insertion follows a route independent in many features from the path of insertion of the 20 classical amino acids. Selenocysteine, therefore, can be considered the 21st amino acid.


  • selenoproteins;
  • selenoenzymes;
  • nonstandard amino acid;
  • tRNASec;
  • translation factor SelB;
  • selenocysteine synthesis;
  • selenophosphate