ACCUMULATION OF XYLITOL IN THE MAMMALIAN LENS IS RELATED TO GLUCURONATE METABOLISM

Cataract remains the major cause of blindness worldwide and a common c omplication of diabetes, Polyol accumulation in the lens is associated with cataract formation, Here me 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 e nzymes 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, Glucu ronate reductase has been purified and was inhibited by thiol quenchin g reagents, UDP-glucuronyl transferase is also present in mammalian le nses; this enzyme may be an anti-toxic defense mechanism in the lens.