Biochemical synthesis of the medicinal sugar l-gulose using fungal alditol oxidase

Some rare sugars can be potently medicinal, such as l -gulose. In this study, we present a novel alditol oxidase (fAldOx) from the soil fungus Penicillium sp. KU–1, and its application for the effective production of l -gulose. To the best of our knowledge, this is the first report of a successful direct conversion of d -sorbitol to l -gulose. We further purified it to homogeneity with a ∼108-fold purification and an overall yield of 3.26%, and also determined the effectors of fAldOx. The enzyme possessed broad substrate specificity for alditols such as erythritol (kcat/KM, 355 m −1 s−1), thus implying that the effective production of multiple rare sugars for medicinal applications may be possible.