The fructose is one of the monosaccharide classified into the ketohexose . 

It is an epimer in 3rd place of the fructose . 

The psicose was isolated from psicofuranine that was the antibiotic, and named.

In the allose and the psicose, the research is the advanced rare sugars.

It is known that there are insulin secretion action and action that prevents arteriosclerosis in the psicose.

A large amount of psicoses are synthesized from the fructose by D-Tagatose 3-epimerase (DTE)
Moreover, it is a departure material to produce various rare sugars.

The isomerization is caused in solution, and it becomes a compound with the ring-shaped structure. (mutarotation). 

It is α-furanose form that the existence ratio is the highest when the talose reaches the condition of equilibrium