2.3- Diphosphoglyceric acid

Examples of considerably more consequence are 1,3-diphosphoglyceric acid in the glycolytic pathway, and succinyl phosphate in the Krebs cycle. These compounds should not trouble us, since their reactivity is easily explained in terms of the above processes. 

For reactions (3.46) and (3.47), 1,3-diphosphoglyceric acid is the general product and provides for energetic conjugation between these reactions [13]. 

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,. 

In certain contemporary organisms, for instance, bacteria and fungi, 3-phospho-D-glyceroyl-phosphate polyphosphate phosphotransferase activity was found (Kulaev and Bobyk, 1971 Kulaev et al., 1971). The phosphate was transferred from 1,3-diphosphoglyceric acid, not to ADP to form ATP, as one could expect from the Meyerhof-Embden-Parnas scheme, but directly to PolyP. This fossil reaction was most expressed in an adenine deficient yeast mutant under cell adaptation to ATP depletion. 

The reaction occurs in three stages. In the first stage, the sul-phydryl group of the enzyme and the NAD are reduced and glyceraldehyde-3-phosphate is phosphorylated by inorganic phosphate to 1,3, diphosphoglyceric acid ... 

The D-glyceraldehyde-3-phosphate is converted into 1,3-diphosphoglyceric acid using inorganic phosphate, and electrons are transferred to the coenzyme NAD" -. The enzyme complex involved is called phosphoglyceraldehyde dehydrogenase. The reaction is the first in the EMP pathway to involve... 

Three of the reactions in the Calvin cycle are irreversible and serve to drive the whole cycle in a clockwise direction. The first step in the cycle can be regarded as the action of carbon dioxide on ribulose-l,5-diphosphate to produce two molecules of 3-phosphoglyceric acid which is then converted into 1,3-diphosphoglyceric acid by the action of ATP and the appropriate enzyme. The important first step is catalysed by the phosphoprotein D-ribulose-1,5 bis phosphate carboxylase oxygenase (RUBISCO) which is probably the most abundant enzyme in the world. 

In the step where 1,3 diphosphoglyceric acid is converted into 3-phosphoglyceric acid and the phosphoenolpyruvic acid is changed to pyruvic acid, ADP is converted into ATP and there is an overall gain of two molecules of ATP per glucose molecule entering the process. 

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+. 

Phosphoglycerate Kinase. The acyl phosphate of 1,.3-diphosphoglyceric acid is transferred to ADP by phosphoglycerate kinase (XVI). This... 

Kulaev (1979) showed that such evolutionary conserved organisms as Micrococcus lysodeicticus and P. shermanii possess a glycolysis-dependent polyphosphate synthesis system in addition to the ATP-dependent one. It has been established (Bobic, 1971 Kulaev et al, 1973) that the biosynthesis of polyphosphates in propionibacteria can proceed both via the terminal phosphate of ATP as well as that of 1,3-diphosphoglyceric acid (1,3-DPGA) ... 

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. 

This reaction can only continue till all the substrate is used up, if the reaction product, which is 1,3-diphosphoglyceric acid, is removed from the solution in the cell, this add then reacts with ADP, converting it into ATP the enei -rich anhydride bond then disappears... 

In the course of reactions 1 to-4, a molecule of glucose has been transformed into a mixture of F—1,6—PP and two triosephosphates. Now occurs the first anaerobic oxido-reduction (see p. 142) in which, in the presence of triosephosphate dehydrogenase and its coenzyme DPN, an internal oxido-reduction takes place forming 1,3-diphosphoglyceric acid, a molecule containing an energy-rich acylphosphate bond. 

When the 1,3-diphosphoglyceric acid is formed, in reaction 5, DPN+ is reduced. The DPNH which results is first of all dehydrogenated by phosphodihydroxyacetone producing 3-phosphoglycerol, which is then hydrolysed by a phosphatase to form glycerol. This is the explanation of... 

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