Involved in cyanogenesis, the release of HCN from injured tissues. Decomposes a varieties of (R) or (S) cyanohydrins into HCN and the corresponding aldehydes and ketones. The natural substrate of this enzyme is (S)-acetone cyanohydrin. a monosubstituted aliphatic (S)-hydroxynitrile = an aldehyde + hydrogen cyanide a disubstituted aliphatic (S)-hydroxynitrile = a ketone + hydrogen cyanide an aromatic (S)-hydroxynitrile = an aromatic aldehyde + hydrogen cyanide Homodimer. The N-terminus is blocked. Belongs to the AB hydrolase superfamily. Hydroxynitrile lyase family.