Glyceraldehyde phosphoric acid

Phosphodihydroxyacetone CHjOH-CO-CHgO-POaHj is a triose ester a triosephosphate. Another member of the same class is its isomeric aldehyde, phosphoglyceraldehyde or 3-glyceraldehyde-phosphoric acid ... 

In subsequent steps, ATP is utilized to phosphorylate the carboxylate group of 3-phosphoglycerate to create 1,3-diphosphoglycerate (a mixed anhydride of glyceric and phosphoric acids). This substance then is reduced by NADPH to glyceraldehyde 3-phosphate ... 

The thiol eater intermediate resulting from oxidation of glyceraldehyde 3-phosphatc next reacts with phosphate ion in a aucicophilic acyl suhstt-cution step (.Section 21.2i to 3neld 3-phosphoglyceroy1 phosphate, a mixed anhydride between a carboxylic aci-d and phosphoric acid. 

I rcpMicil hy hiMlIn ii mixluic of l.l imilcx ol phosphoiyl chloridu imil 2 inolcs uf phenol lo 180 iind distilling the product. It is used Tor the preparation of dl-glyceraldehyde 3-phosphoric acid, and dihydroxyacetone phosphate," and diphenyl-... 

Junowicz-Kocholaty. J. Biol. Chem. 149, 71 (1943) by reductive cleavage of glyceraldehyde 1-benzyl ether 3-phosphoric acid Fischer, Baer, Ber. 65, 337. 1040 (1932) by hydrolysis of dimeric gylceraldehyde 1,3 -diphosphoric acid Baer, Fischer, J. BioL Chem. 150, 213 (1943) by hydrolysis of dimeric glyceraldehyde 1-bromide 3-phosphoric acid ibid. 223. See also Baer in Biochem. Prepn. I, 50 (1949). Prepn of D-form by enzymatic route Meyerhof, Junowicz-Kocholaty, toe. cit by synthetic route Ballou, Ftscher, J. Am. Chem. Soc. 77, 3329 (1955). 

Glyceraldehyde-3-phosphate dehydrogenase is an example of an enzyme that uses NAD as an oxidizing coenzyme. The enzyme catalyzes the oxidation of the aldehyde group of glyceraldehyde-3-phosphate (GAP) to an anhydride of a carboxylic acid and phosphoric acid. This is a reaction that occurs in glycolysis (Figure 25.3). 

Glyceraldehyde-3-phosphate, in turn, is converted to 1,3- l5phosphoglycerate in a reaction that converts the aldehyde to carboxylic acid involved in a mixed anhydride linkage to phosphoric acid. 

Glyceraldehyde-3-phosphate, an important compound in the cellular oxidation of carbohydrates, is an ester of phosphoric acid and glyceraldehyde. 

Scheme 9.6. A cartoon representation of the enzyme (named glyceraldehyde-3-phosphate dehydrogenase, EC 1.2.1.12) catalyzed oxidation of the aldehyde glyceraldehyde-3-phosphate to the carboxylic acid-phosphoric acid mixed anhydride, 1,3-bisphosphoglycerate (which can be hydrolyzed to the corresponding carboxyhc acid and phosphoric acid). Start in a clockwise direction from the npper left.

The aldehyde group of glyceraldehyde-3-phosphate is oxidized by NAD, forming 1,3-bisphosphoglycerate. In this reaction, the aldehyde is oxidized to a carboxylic acid, which then forms an ester with phosphoric acid. We looked at the mechanism of this reaction in Section 24.1. 

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