Function
Involved in the biosynthesis of D-psicose. Catalyzes the reversible epimerization of D-fructose at the C3 position to yield D-psicose. The enzyme is highly specific for D-psicose and shows very low activity with D-tagatose. The substrate specificity decreases in the following order: D-fructose, D-tagatose, D-ribulose, D-xylulose, and D-sorbose. It shows a higher level of activity for cis ketoses than for trans-ketoses.