Fructose 6-Phosphate Neuberg Ester

This ester was first prepared 209) by partial hydrolysis of D-fructose diphosphate and later isolated by Robison 210) from the hexose monophosphate fraction obtained by yeast juice fermentation. 

The phosphate group at carbon 1 of D-fructose 1,6-diphosphate is hydrolyzed in 1 AT acid, at 100°C., approximately 12 times as fast as that at carbon 6. Although at this temperature some destruction of the D-fructose occurs, a fairly good yield of the ester can be obtained by this method. An improved procedure whereby the hydrolysis is carried out at a lower temperature is given by Neuberg, Lustig, and Rothenberg 211). 

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Fructose 6-phosphate, Neuberg ester an intermediate in Glycolysis (see) produced by isomerization of glucose 6-phosphate. It is also formed from erythrose 4-phosphate by transketolation. 

A number of hexose phosphates have been isolated from natural sources. Of these oTructose 1,6-diphosphate (Harden-Young ester) (I), D-fructose 6-phosphate (Neuberg ester) (II), D-glucose 6-phosphate (Robison ester) (III), and a-D-glucose 1-phosphate (IV) are of particular biochemical importance in the processes of fermentation and glycolysis. These hexose phosphates are interconvertible in the presence of the proper enzymes and cofactors. 

Fructose Monophosphate.— This ester has been obtained by Neuberg from the 1 6-diphosphate by partial hydrolysis. Unlike the diphosphate, it is fermented by yeast. Neuberg s ester is one of the two hexose phosphates found in muscle. 

Glucose Monophosphates.—A crude monophosphate (Robison s ester) has been obtained by the action of yeast juice on glucose or fructose. It is a mixture of fructose monophosphate (Neuberg s ester) and glucopyranose-6-phosphoric acid (Embden s ester). The two esters have been separated by fractional crystallisation of their brucine salts. A glucopyranose-1-monophosphate (Cori s ester) is obtained by the action of phosphate on minced muscle. 

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