Glucose 6-Phosphate Robison Ester

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. 

Glucose-6-phosphate Robison ester)—Although the existence of this ester had been known since 1914 from experiments on yeast carried out by Harden and Robison, it was not until 1931 that Robison and King succeeded in obtaining it in the pure state. 

It has long been known that fermentation by yeast extracts normally comprises at least three phases an initial induction period followed, within a matter of about five or ten minutes, by a very rapid fermentation this persists for some time and passes over into a prolonged relatively slow action. All this has been measured by carbon dioxide production. This is true not only for glucose, shown, e.g., by Meyerhof (53,54), but also for galactose (40) and for fructose (34). These have been attributed to the formation of the hexose-6-phosphate (Robison ester) which must precede any carbon dioxide liberation, and the conversion of this to hexose-1,6-diphosphate (Harden-Young ester), which ferments slowly. The maximum of hexose-6-phosphate concentration coincides with the maximum car-... 

Glucose-6-phosphate. D-Gfucose 6-<dihydrogen phosphate) glucose-6-phosphoric acid Robison ester. C4-HijOjP mol wt 260.14. C 27-70%, H 5.04%, O 55.35%, P... 

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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