Highly Selective Isomerization of Glucose into Fructose Catalyzed by a Mimic Glucose Isomerase

An amphoteric phenolic compound with carboxyl and amino functional groups was synthesized and used as mimic glucose isomerase to catalyze the isomerization of glucose into fructose. The mimic enzyme displayed excellent catalytic activity for isomerization of glucose to fructose under mild conditions. The yield of fructose and selectivity of fructose could reach 33.0% and 93.5% after reacting 4h, respectively, at pH8.5 and 80 degrees C. The catalysis reaction rate constant k(cat) and Michaelis constants K-mG, K-mF were calculated. The activation energy of glucose to fructose was evaluated as 65.9kJmol(-1). The possible catalysis reaction mechanism was proposed. The acid-base groups on the catalyst play an important role in proton extraction and transfer, as well as in the rotation of local carbon chain, which leads to the highly selective isomerization of glucose into fructose under mild conditions.