Neuberg ester

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. 

Neplanocin B, N-30 Neplanocin C, N-31 Neplanocin D, N-32 Netilmicin sulfate, N-33 Netilmicin, N-33 Netivudine, N-34 Netromycin, N-33 Neu5Ac, A-20 Neuberg ester, F-89 Neu5NAc, A-20 Neuraminic acid, N-35 Neuraminic acids, S-37... 

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. 

Neely, W. Brock, Dextran Structure and Synthesis, 15, 341 — 369 Neely, W. Brock, Infrared Spectra of Carbohydrates, 12, 13 — 33 Neuberg, Carl, Biochemical Reductions at the Expense of Sugars, 4, 75—117 Neufeld, Elizabeth F., and Hassid, W. Z., Biosynthesis of Saccharides from Glycopyranosyl Esters of Nucleotides ( Sugar Nucleotides ), 18, 309 - 356... 

Specificity vs. general applicability An enzyme is generally perceived to be loo specific to be of use for any other reaction. This is not always true, for many enzymes are known to catalyze a wide range of reactions, for example, lipases and proteases catalyze the hydrolysis of a number of esters and proteins (Inouye et al., 1979 Posorske, 1984 Neuberger and Brocklehurst, 1987), and peroxidases catalyze a wide variety of substrates (Saunders el al., 1964 Musso, 1967 Dordick et al., 1987). 

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). 

Ethyl j -oxoadipate heated 4.5 hrs. at 140 with benzyl alcohol in a slow Ng-stream to remove the ethanol liberated -> a-benzyl -ethyl j -oxoadipate. Y 79%.—In the absence of catalysts, transesterification occurs with esters of y -ketoacids, but not with esters of ordinary aliphatic acids. W. G. Laver, A. Neuberger, and J. J. Scott, Soc. 1959, 1474. 

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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