Enzymatic Conversion of Galactose Polymers into Copolymers Containing Galactonic Acid by Glucose Oxidase.

Sugar oxidase can oxidize a carbohydrate substrate into an acid, but there have been no reports on the successful enzymatic conversion of glycopolymers containing carbohydrate pendants. We introduced a poly(ethylene glycol) (PEG) spacer between the carbohydrate and the methacrylic units, and glucose oxidase (GOx) showed enzymatic activity when the PEG spacer is sufficiently long, converting the galactose pendant into galactonic acid and yielding a copolymer. The glycopolymers with a PEG spacer showed stronger binding to the sugar-specific lectin than those without the spacer, while the binding was gradually weakened as the sugar pendants were converted to acid groups. To the best of our knowledge, this is the first example to use a hydrophilic PEG spacer to enzymatically convert a substrate attached on a polymer chain. The enzymatic conversion of such glycopolymers represents a useful green chemistry approach to obtain copolymers based on carbohydrates.