Fructose 6-phosphate

Fructose 6-phosphate (also known as the Neuberg ester) is fructose sugar phosphorylated on carbon 6 (ie. is a fructosephosphate). The β- D -form of this compound is very common in cells, the vast majority of glucose and fructose entering a cell will become converted to this at some point. The name Neuberg ester comes from the German biochemist Carl Neuberg.

History
In 1918, Carl Neuberg found that the compound (only later identified as fructose 6-phosphate) could be produced by mild acid hydrolysis of "Harden-Young ester" (fructose 2,6-bisphosphate).

Fructose 6-phosphate in glycolysis
Fructose 6-phosphate lies within the glycolysis metabolic pathway and is produced by isomerisation of glucose 6-phosphate. It is in turn further phosphorylated to fructose-1,6-bisphosphate.

Fructose 6-phosphate isomerism
Fructose 6-phosphate has only one biologically active isomer, the β- D -form. There are many other isomers, analogous to those of fructose.