Our goal is to determine the mechanisms of the nitrilase superfamily enzymes. These enzymes have common features such as their fold and conserved residues in their active sites (two glutamates, a lysine and a cysteine) but have a range of different activities. Most of the enzymes in the superfamily are amidases that convert amides to the corresponding carboxylic acid and ammonia. The nitrilases that convert nitriles to carboxylic acids and ammonia form spiral homo-oligomeric structures and, to date, none have crystallized in their complete, active form. The spiral structures are, however, amenable to structure determination by cryoEM and we have determined high-resolution structures of four of them of which one has been published. The enzyme in our current study is an interesting fungal homologue, the cyanide hydratase, which converts cyanide (HCN) to formamide Further study and structural analysis is necessary to elucidate the details of the full reaction mechanism.