Arginine-catalyzed isomerization of ribose to ribulose

Abstract

Arginine, one of the basic amino acids known as green catalysts for sugar isomerization, was used to isomerize ribose to ribulose, a rare keto-pentose sugar, and the effects of reaction conditions on the yield of ribulose and degree of browning were investigated using a batch-type reactor. The initial pH of the mixture of ribose and arginine was in the range of 9.39–10.01. A high yield of ribulose and low degree of browning of the reaction mixture were achieved at a molar ratio of arginine to ribose of 0.05 and a temperature of 110 °C. To achieve the highest possible ribulose concentration, an initial ribose concentration of 0.75 mol/L was preferable. It was found that once isomerization had progressed, acidic by-products caused a reduction in pH and brown-colored compounds were continuously formed. This study showed that the method used is relatively simple and effective for producing ribulose.