Gluconic acid-6-phosphate

Adding glucose-6-phosphate dehydrogenase (G-6-PDH) in the presence of oxidized nicotinamide adenine trinucleotide (NADH) yields gluconic acid-6-phosphate and an equivalent amount of the reduced form, NADPH. The amount of NADPH can be measured from its absorbance at 340 nm. For fructose the first reaction is ... 

The discovery that D-gluconic acid 6-phosphate may be degraded enzymatically to D-ribose 5-phosphate17,18 has thrown light on a possible path for the biogenesis of D-ribose. 

D-Ribulose 5-phosphate is found together with D-ribose 5-phosphate as an oxidation product of n-gluconic acid 6-phosphate with a purified yeast enzyme (221-223). The D-ribulose 5-phosphate was identified as the o-nitrophenylhydrazone derivative, having a specific rotation in methanol of 50 5°. D-Ribulose 5-phosphate appears to be the precursor of D-ribose in yeast and rat liver. A D-ribulose diphosphate was detected in the products formed during the first few seconds of photosynthesis (224) ... 

A 3-deoxy-2-ketogluconic acid 6-phosphate was isolated as an intermediate in the enzymic oxidation of gluconic acid 6-phosphate 135a). The formation of this acid by a dehydration mechanism is reminiscent of that of the saccharinic acids. 

Several other pathways of glucose catabolism have been discovered in different microorganisms. In Pseudomonas saccharophila it was observed (100) that D-gluconic acid 6-phosphate was degraded to pyruvic acid and triose phosphate. It was postulated that an intermediate 2-keto-3-deoxy-D-gluconic acid 6-phosphate was formed. Subsequently this intermediate was isolated and characterized (101). The following pathway was suggested. 

The enthalpies for the hydrolysis of a number of glycoside and nucleoside cyclic phosphates have been measured. Photolysis of the disodium salt of a-D-glucopyranose 6-phosphate in aqueous solution furnished a number of products, including D-gluconic acid 6-phosphate, D-arabinofuranose 5-phosphate, D-glyceric acid 3-phosphate, glycolic acid phosphate, phosphoric acid, and... 

D-Gluconic acid 6-phosphate (8), (20) Purification of glycerol 3-phosphate dehydrogenase 83... 

Gluconic acid 6-phosphate may be obtained from glucose 6-phosphate with a dehydrogenase and TPN. Glucosamine 6-phosphate can be prepared from glucose 6-phosphate and glutamine. 

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