NO, thiols and disulfides.

The chemical nature of the messenger molecule, nitric oxide (NO), and especially its reactivity towards thiol groups and disulfides, could explain, at least partly, its intervention in so many different biological processes. NO can be regarded as the smallest molecule suitable for electron transport in biological systems. The S-nitrosation reaction and its reverse reaction represent the most convenient general way to store, to transport and finally to release NO. Nitric oxide is also particularly convenient for playing a role in interconversions of thiol groups and disulfides in chain radical or oxidation-reduction processes, and to be subsequently engaged in complex sequences of reactions accounting for different biological situations.