The structure of the galactosephosphate present in the liver during galactose assimilation

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Abstract
The mixture of phosphoric esters isolated from the livers of rabbits assimilating galactose was subjected to alkaline hydrolysis in order to remove reducing hexosephosphates. The product obtained in this way contained 29.6% anhydrous Ba galactose-1-phosphate, 3.4% anhydrous Ba glucose-1-phosphate and 2% Ba salt of an unidentified acid-labile ester; the remainder consisted of a difficultly hydrolysable non-reducing ester. The Ba salts of the ester mixture freed from reducing phosphates had [alpha]546i + 34.4[degree] and the Ba salt of the difficultly hydrolysable ester [alpha]5461[long dash]3.4[degree]. From these values it was calculated that the natural anhydrous Ba galactose-1-phosphate has [alpha]5461 + 113[degree], while the synthetic product has [alpha]5461 +109.5[degree]. The velocity constant (k) of hydrolysis of the acid-labile fraction of the ester mixture, freed from reducing phosphates, in 0.25 N HC1 at 25[degree] was 0.79 X 10-3. From this value the k of the natural galactose-1-phosphoric acid was calculated to be 0.91 X 10-3, while the k of the synthetic product is 0.89 X 10-3. These results strongly suggest that the natural and synthetic galactose-1-phosphoric acid are identical. The ester probably is an a-pyranoside as is the natural glucose-1-phosphoric acid.