NUDIX hydrolases are a superfamily of hydrolytic enzymes capable of cleaving nucleoside diphosphates linked to x (any moiety), hence their name.[1][2][3][4] The reaction yields nucleoside monophosphate (NMP) plus X-P. Substrates hydrolysed by nudix enzymes comprise a wide range of organic pyrophosphates, including nucleoside di- and triphosphates, dinucleoside and diphosphoinositol polyphosphates, nucleotide sugars and RNA caps, with varying degrees of substrate specificity.[3] Enzymes of the NUDIX superfamily are found in all types of organisms, including eukaryotes, bacteria and archaea.[3]
There are two components to the NUDIX family: the so-called NUDIX fold of a beta sheet with alpha helices on each side and the NUDIX motif which contains catalytic and metal-binding amino acids. The Nudix motif is GXXXXXEXXXXXXXREUXEEXGU where U is isoleucine, leucine or valine, and X is any amino acid. This forms a short helix which (usually) contains the catalytic amino acids. NUDIX hydrolases include Dcp2 of the decapping complex, ADP-ribose diphosphatase, MutT, ADPRase, Ap4A hydrolases, RppH, and many others.[5]