transnitrosylation

Transnitrosylation, also called transnitrosation, is a biochemical process in which a nitroso group (NO+) is transferred from one S-nitrosothiol to another thiol, generating a new S-nitrosothiol and a free thiol.

The exchange reaction can occur between low-molecular-weight S-nitrosothiols, such as S-nitrosoglutathione (GSNO), and protein thiols, or between two protein thiols, depending on redox conditions and the relative reactivity of the thiols.

In cells, transnitrosylation is a mechanism for spreading nitric oxide signaling and regulating protein function by introducing or relocating S-nitrosyl groups. The nitroso group can modulate enzyme activity, protein–protein interactions, and localization, with effects that depend on the specific donor and target.

Transnitrosylation is reversible and can be counteracted by denitrosylation pathways, including thioredoxin- and glutaredoxin-mediated processes. The overall cellular balance of transnitrosylation and denitrosylation contributes to redox signaling and nitrosothiol homeostasis.

Detection and study of transnitrosylation rely on biochemical assays and mass spectrometry, with experimental conditions such as metal ions and pH influencing reaction rates and outcomes.