Identification of Key Intermediates during the NO and H₂S Crosstalk Signaling Pathways

The stable isomers and electronic states of [S,S,N,O]^- species are investigated with a special focus on the most relevant isomers that could be involved in the NO/H₂S cross-talk pathways in biological media. This work identifies eight stable anions, among which are the already known cis-SSNO^- and trans-SSNO^- molecules and a new NO₃^--like anionic species, NS₂O^-. Our computations show that the previously determined structure in lab experiment is trans-SSNO^-, which is not relevant for biological activity in vivo. Instead, NS₂O^- is proposed as the most likely key intermediate in vivo during important biological processes. This result alleviates the corresponding controversy in the literature.