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Ludger A. Wessjohann, Alex Schneider, Muhammad Abbas, Wolfgang Brandt
Selenium in chemistry and biochemistry in comparison to sulfur
Keywords: disulfide/diselenide/selenenylsulfide interchange, enzyme mechanisms, selenocysteine, selenoproteins, Synthesis
What makes selenoenzymes – seen from a chemists view – so special that they cannot be substituted by just more analogous or adapted sulfur proteins? This review compiles and compares physicochemical properties of selenium and sulfur, synthetic routes to selenocysteine (Sec) and its peptides, and comparative studies of relevant thiols and selenols and their (mixed) dichalcogens, required to understand the special role of selenium in selenoproteins on the atomic molecular level. The biochemically most relevant differences are the higher polarizability of –Se- and the lower pKa of –SeH. The latter imposes a strikingly different pHdependence than thiols, with selenols being active at much lower pH. Finally, selected typical enzymatic mechanisms which involve selenocysteine are critically discussed, also in view of the authors' own results.
Biological Chemistry, Walter de Gruyter
Print ISSN: 1431-6730
Volume: 2007
Pages: -