Modeling of Selenoprotein Nitrozation: Synthetic Approaches

Model reactions have been carried out to evaluate the question of what kind of links may exist between the biological cycles of nitrogen oxide (NO) and those of selenoproteins, especially the amino acid selenocysteine (Sec). To collect information about the properties of the as-yet unknown selenonitrites (RSeNO) in comparison with the well-known thionitrites, (RSNO), the interaction of nitrosating reagents with a choice of molecular thiols and related selenoles as model compounds have been studied. Selenol nitrosation is clearly preferred in vitro to thiol nitrosation, but selenonitrites are thermally significantly less stable than the related thionitrites, suggesting that selenonitrites may be important, but yet-undetected intermediates in selenoprotein chemistry. Chemical trapping of RSeNO was achieved for the first time by its 1,4-addition to dimethylbutadiene leading to a stable unsaturated oxime.