is the chemical compound
with the formula ONSC(CH3
H (Ac = acetyl
). The molecule is an important donor of the NO+
. It has received much attention because nitric oxide
and some organic nitroso derivatives serve as signaling molecules in living systems, especially related to vasodilation
. SNAP is used as a model for the general class of S-nitrosothiols. S-Nitrosoglutathione
is a related agent.
Organic chemistry background
SNAP is derived from the amino acid penicillamine
. The prefix "S" indicates that the NO group is attached to sulfur.
Nitrosothiols contain the RS-N=O functional group (R = alkyl, aryl). The S-N-O angle deviates strongly from 180° because the nitrogen atom bears of lone pair of electrons.
Thionitroso compounds arise from condensation from nitrous acid and a thiol:
- RSH + HONO → RSNO + H2O
Many other methods exist for their synthesis. Once formed, these deeply coloured compounds are often thermally unstable with respect to formation of the disulfide
and nitric oxide.
SNAP releases NO+ upon treatment with acids:
- RSNO + H+ → RSH + NO+
Thionitroso compounds transfer NO to other thiols
- RSNO + R'SH → RSH + R'SNO