6] Erythrose 4-phosphate

Abstract

This chapter discusses the determination of erythrose 4-phosphate. The procedure consists of the oxidation of glucose 6-phosphate with lead tetraacetate, separation of the product, erythrose 4-phosphate from glucose 6-phosphate by chromatography on Dowex 1 formate, and preparation of the stable hydrazone that is recovered as the barium salt. Less than the theoretical amount of lead tetraacetate is used to avoid overoxidation and production of glyceraldehyde 3-phosphate. Barium glucose 6-phosphate heptahydrate (1 millimole, 0.53 g) is placed in a 500-ml beaker and moistened with 2 ml of water. Then 5 ml of glacial acetic acid, reagent grade, is added, and the suspension is warmed to 50–60° for a few minutes to dissolve the salt. Sulfuric acid (0.35 ml of 6 N ) is added with stirring and is followed by 245 ml of glacial acetic acid. The barium salt is precipitated with 3 volumes of ethanol, recovered, washed and dried, that yields 0.5 millimole of erythrose 4-phosphate. Theproduct does not contain glucose 6-phosphate or glyceraldehyde 3-phosphate. The barium salt of erythrose 4-phosphate hydrazone is quite stable and may be stored for long periods of time in the refrigerator.