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| Names | |
|---|---|
| IUPAC name Phosphono 2-hydroxy-3-phosphonooxypropanoate | |
| Systematic IUPAC name (2-Hydroxy-3-phosphonooxy-propanoyloxy)phosphonic acid | |
| Other names 1,3-Diphosphoglycerate; Glycerate-1,3-bisphosphate; Glycerate-1,3-biphosphate; 1,3-Biphosphoglycerate; 3-Phosphoglyceroyl phosphate; Glyceric acid-1,3-diphosphate | |
| Identifiers | |
3D model (JSmol) | |
| Abbreviations | 1,3BPG; 1,3-BPG; PGAP |
| ChEBI | |
| ChEMBL | |
| ChemSpider |
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| KEGG | |
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| Properties | |
| C3H8O10P2 | |
| Molar mass | 266.035 g·mol−1 |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
1,3-Bisphosphoglyceric acid (1,3-Bisphosphoglycerate or1,3BPG) is athree-carbon organic molecule present in most, if not all,living organisms.[1][2][3] It primarily exists as ametabolic intermediate in bothglycolysis duringrespiration and theCalvin cycle duringphotosynthesis. 1,3BPG is a transitional stage betweenglycerate 3-phosphate andglyceraldehyde 3-phosphate during the fixation/reduction ofCO2. 1,3BPG is also a precursor to2,3-bisphosphoglycerate which is formed in the Luebering–Rapoport shunt of glycolysis inred blood cells.[4]
1,3-Bisphosphoglycerate is theconjugate base of 1,3-bisphosphoglyceric acid. It is phosphorylated at the number 1 and 3 carbons. The result of this phosphorylation gives 1,3BPG important biological properties such as the ability to donate aphosphate group toadenosine diphosphate (ADP) in order to form the energy storage moleculeadenosine triphosphate (ATP).
CompoundC00118 atKEGG Pathway Database.Enzyme1.2.1.12 atKEGG Pathway Database.CompoundC00236 atKEGG Pathway Database.Enzyme2.7.2.3 atKEGG Pathway Database.CompoundC00197 atKEGG Pathway Database.
1,3BPG is amacroergic metabolic intermediate in theglycolytic pathway. It is created by theexergonicoxidation of thealdehyde inglyceraldehyde 3-phosphate. The result of this oxidation is the conversion of the aldehyde group into acarboxylic acid group which drives the formation of an acyl phosphate bond. The latter reaction is the only step in the glycolytic pathway in whichNAD+ is converted intoNADH. The formation reaction of 1,3BPG requires the presence of an enzyme calledglyceraldehyde-3-phosphate dehydrogenase.
Thehigh-energy acyl phosphate bond of 1,3BPG is important inrespiration as it assists in the formation ofATP. The molecule of ATP created during the following reaction is the first molecule produced during respiration. The reaction occurs as follows;
The transfer of aninorganic phosphate from the carboxyl group on 1,3BPG to ADP to form ATP is reversible due to a lowΔG. This is as a result of one acyl phosphate bond being cleaved whilst another is created. This reaction is not naturally spontaneous and requires the presence of acatalyst. This role is performed by theenzymephosphoglycerate kinase. During the reaction phosphoglycerate kinase undergoes a substrate induced conformational change similar to another metabolic enzyme calledhexokinase.
Because two molecules of glyceraldehyde-3-phosphate are formed during glycolysis from one molecule of glucose, 1,3BPG can be said to be responsible for two of the ten molecules of ATP produced during the entire process. Glycolysis also uses two molecules of ATP in its initial stages as acommitted and irreversible step. For this reason glycolysis is not reversible and has a net produce of 2 molecules of ATP and two of NADH. The two molecules of NADH themselves go on to produce approximately 3 molecules of ATP each.
Click on genes, proteins and metabolites below to link to respective articles.[§ 1]
1,3-BPG has a very similar role in theCalvin cycle to its role in the glycolytic pathway. For this reason both reactions are said to be analogous. However the reaction pathway is effectively reversed. The only other major difference between the two reactions is that NADPH is used as an electron donor in the calvin cycle whilst NAD+ is used as an electron acceptor in glycolysis. In this reaction cycle 1,3BPG originates from3-phosphoglycerate and is made intoglyceraldehyde 3-phosphate by the action of specific enzymes.
Contrary to the similar reactions of the glycolytic pathway, 1,3BPG in the Calvin cycle does not produce ATP but instead uses it. For this reason it can be considered to be an irreversible and committed step in the cycle. The outcome of this section of the cycle is an inorganic phosphate is removed from 1,3BPG as a hydrogen ion and two electrons are added to the compound+.
In complete reverse of the glycolytic pathway reaction, the enzyme phosphoglycerate kinase catalyses the reduction of thecarboxyl group of 1,3BPG to form analdehyde instead. This reaction also releases aninorganic phosphate molecule which is subsequently used as energy for the donation of electrons from the conversion of NADPH to NADP+. Overseeing this latter stage of the reaction is the enzyme glyceraldehyde-phosphate dehydrogenase.
During normalmetabolism in human erythrocytes, ≈19% of the 1,3BPG produced does not go any further in the glycolytic pathway.[5] It is instead shunted through theLuebering–Rapoport pathway involving the reduction of ATP in thered blood cells. During this alternate pathway it is made into a similar molecule called2,3-bisphosphoglyceric acid (2,3BPG).[4] 2,3BPG is used as a mechanism to oversee the efficient release ofoxygen fromhemoglobin. Levels of this 1,3BPG will raise in a patient's blood when oxygen levels are low as this is one of the mechanisms ofacclimatization. Low oxygen levels trigger a rise in 1,3BPG levels which in turn raises the level of 2,3BPG which alters the efficiency of oxygen dissociation from hemoglobin.
