Substrate binding in the FAD-dependent hydroxynitrile lyase from almond provides insight into the mechanism of cyanohydrin formation and explains the absence of dehydrogenation activity.

In a large number of plant species hydroxynitrile lyases catalyze the decomposition of cyanohydrins in order to generate hydrogen cyanide upon tissue damage. Hydrogen cyanide serves as a deterrent against herbivores and fungi. In vitro hydroxynitrile lyases are proficient biocatalysts for the stereospecific synthesis of cyanohydrins.