Selenopeptide chemistry.

This review focuses on the chemical aspects of the 21st proteinogenic amino acid, selenocysteine in peptides and proteins. It describes the physicochemical properties of selenium/sulfur and selenocysteine/cysteine based on comprehensive structural (X-ray, NMR, CD) and biological data, and illustrates why selenocysteine is considered the most conservative substitution of cysteine. The main focus lies on the synthetic methods on selenocysteine incorporation into peptides and proteins, including an overview of the selenocysteine building block syntheses for Boc- and Fmoc-SPPS. Selenocysteine-mediated reactions such as native chemical ligation and dehydroalanine formation are addressed towards peptide conjugation. Selenopeptides have very interesting and distinct properties which lead to a diverse range of applications such as structural, functional and mechanistic probes, robust scaffolds, enzymatic reaction design, peptide conjugations and folding tools. Copyright 2008 European Peptide Society and John Wiley & Sons, Ltd.