Abstract
A new type of sorbitol oxidase which converts sorbitol to glucose in the absence of NAD or NADP was found in the leaf of the apple. The partially purified enzyme consumed 1/2 mole of oxygen in converting one mole of sorbitol to glucose (sorbitol+1/2 O2 → glucose+H2O). The enzyme had its optimum activity at pH 4.0, and it had a Km value of 100 mM for sorbitol and showed a weak dependency on divalent cations. This sorbitol oxidase seems to play an important role in the utilization of accumulated sorbitol.