The enzyme (R)-mandelonitrile lyase (EC 4.1.2.10, (R)-HNL, (R)-oxynitrilase, (R)-hydroxynitrile lyase) catalyzes the chemical reaction mandelonitrile hydrogen cyanide + benzaldehyde This enzyme belongs to the family of lyases, specifically the aldehyde-lyases, which cleave carbon-carbon bonds. The systematic name of this enzyme class is mandelonitrile benzaldehyde-lyase (hydrogen cyanide-forming). Other names in common use include hydroxynitrile lyase, (R)-oxynitrilase, oxynitrilase, D-oxynitrilase, D-alpha-hydroxynitrile lyase, and mandelonitrile benzaldehyde-lyase. This enzyme participates in . It has 2 cofactors: flavin, and flavoprotein.