The enzyme from the rust fungus Uromyces fabae can use D-arabinitol and D-mannitol as substrates in the forward direction and D-xylulose, D-ribulose and, to a lesser extent, D-fructose as substrates in the reverse direction. This enzyme carries out the reactions of both EC 1.1.1.11, D-arabinitol 4-dehydrogenase and EC 1.1.1.250, D-arabinitol 2-dehydrogenase, but unlike them, uses NADP+ rather than NAD+ as cofactor. D-Arabinitol is capable of quenching reactive oxygen species involved in defense reactions of the host plant.
