Fructose-6-phosphate (Fructose-6-phosphate, F6P) is a fructose molecule in which the carbon at position 6 is phosphorylated. β-D type molecules are abundant in cells. Most of the glucose and fructose taken up by cells is converted to this form. Also known as Neuberg Ester, it is named after the German biochemist Carl Neuberg.
In 1918, Carl Neuberg discovered that a substance was produced by the slow acid hydrolysis of fructose-2,6-bisphosphate, then called Harden-Young Ester. This substance was later identified as F6P.
F6P appears in glycolysis and is produced by the isomerization of glucose-6-phosphate. It is later converted to fructose-1,6-bisphosphate.
Of the F6P isomers, only β-D type has bioactivity. There are many other isomers of F6P that correspond to fructose isomers.