Preparation and spectroscopic identification of methyl-Se-nitrososelenol

Modeling Selenoprotein Se-Nitrosation: Synthesis of a Se-Nitrososelenocysteine with Persistent Stability

The Se-nitrosation in selenoproteins such as glutathione peroxidase and thioredoxin reductase to produce Se-nitrososelenocysteines (Sec-SeNOs) has been proposed to play crucial roles in signaling processes mediated by reactive nitrogen species and nitrosative-stress responses, although chemical evidence for the formation of Sec-SeNOs has been elusive not only in proteins but also in small-molecule systems. Herein, we report the first synthesis of a Sec-SeNO by employing a selenocysteine model system that bears a protective molecular cradle. The Sec-SeNO was characterized using ¹H and ⁷⁷Se nuclear magnetic resonance as well as ultraviolet/visible spectroscopy and found to have persistent stability at room temperature in solution. The reaction processes involving the Sec-SeNO provide experimental information that serves as a chemical basis for elucidating the reaction mechanisms involving the SeNO species in biological functions, as well as in selenol-catalyzed NO generation from S-nitrosothiols.

Generation and reactivity of vinyltelluryl radical

Vinyltelluryl radical was prepared by high-vacuum flash pyrolysis from the corresponding divinylditelluride and trapped in an argon matrix at 10 K. The title compound was characterized by IR and UV/Vis spectroscopy, and all experimental data match well with density functional theory at the UB3LYP/def2-QZVPP level. According to UB3LYP/def2-QZVPP computations, the spin density is mainly localized on the Te atom. The vinylogy principle for the vinyltelluryl radical is not applicable due to the lack of delocalization of spin density. Upon irradiation of the matrix with light (λ = 365 nm), the vinyltelluryl radical rearranges to a H-Te˙⋯acetylene complex. Doping the matrix with molecular oxygen leads to the hitherto unknown vinyltelluro peroxy radical. The latter isomerizes to the more thermodynamically stable vinyltelluroyl radical by irradiation with light at λ = 523 nm.