A new action of anion exchange resins on the lactone ring of some carbohydrates

Accumulation of xylitol in the mammalian lens is related to glucuronate metabolism

Cataract remains the major cause of blindness worldwide and a common complication of diabetes. Polyol accumulation in the lens is associated with cataract formation. Here we present evidence for a novel pathway for xylitol production in the lens involving glucuronate metabolism. Xylitol can be produced in rat and bovine lens from glucose, via the enzymes myo-inositol-oxygen oxidoreductase, D-glucuronate reductase, L-gulonate NAD(+)-3-oxidoreductase and L-iditol-NAD(+)-5-oxidoreductase, which have been found in the mammalian lens for the first time. Glucuronate reductase has been purified and was inhibited by thiol quenching reagents. UDP-glucuronyl transferase is also present in mammalian lenses; this enzyme may be an anti-toxic defense mechanism in the lens.