1,3-Diphosphoglyceric acid oxidation

Acetyl-CoA is a positive effector of pyruvate carboxylase, a biotin enzyme. The correct answer is 1,3-diphosphoglyceric acid. It is produced by the oxidation of glyceraldehyde-3-phosphate in the presence of P,. 

A most significant stage in glycolysis is the oxidation of 3-phosphoglyceraldehyde to 1,3 diphosphoglyceric acid utilising NAD+ which is reduced to NADH. There is, however, no overall oxidation in the glycolysis process, since in a later step in the pathway, pyruvic acid is reduced to lactic acid with NADH which is itself re-oxidised to NAD+. 

An example of this type of genesis of pyrophosphate linkages is furnished by the oxidation of phosphoglyceraldehyde to 1,3-diphosphoglyceric acid, an oxidation which occurs during glycolysis. 

He has observed the presence of glutathione in the crystalline enzyme and has thus strengthened the concept that an addition product of the aldehyde and sulfhydryl portion of the enzyme is oxidized and then cleaved by inorganic phosphate to yield 1,3-diphosphoglyceric acid. The inhibitory role of arsenate in this reaction is accounted for by the production of the highly unstable l-arsenyl-3-phosphoglyceric acid. 

The major source of the high energy phosphate found in all of the nucleoside polyphosphates is ATP, and its synthesis can be largely accounted for by oxidative phosphoiylation and by the transfer of phosphate from 1,3-diphosphoglyceric acid and phosphoenolpyruvate to adenosine diphosphate (ADP). However free ribo- and deoxyribonucleoside polyphosphates of the purine and pyrimidine series are found in tissues 98-102). The means by which nucleoside polyphosphates other than those of the adenosine series acquire their phosphate will now be discussed. 

It has been known for sometime that in the oxidation of phospho-glyceraldehyde to phosphoglyceric acid, ADP is required. Closer inspection indicated that two independent enzyme systems are involved, one being triosephosphate dehydrogenase which catalyzes the formation of 1,3-diphosphoglyceric acid, and the other a specific enzyme responsible for the transfer of the phosphate of 1,3-diphosphoglyceric acid to ADP. Adenylic acid is inert except in the presence of adenylic kinase. 

Examples of reactions generating NADH include the conversion of isocitrate into ketoglutarate, and malate into oxaloacetate in the Krebs cycle (Figure 11.21), the oxidation of fatty acids (11.96), the conversion of glyceraldehyde-3-phosphate into 1,3-diphosphoglycerate in glycolysis (Figure 11.20), and reaction... 

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