Glyceraldehyde 3-phosphate

Glyceraldehyde 3-phosphate
Identifiers
CAS number 142-10-9 N
PubChem 729
ChemSpider 709 Y, 393755 (L isomer), 388314 (D isomer)
KEGG C00661 Y
MeSH Glyceraldehyde+3-Phosphate
ChEBI CHEBI:17138 Y
Jmol-3D images Image 1
Properties
Molecular formula C3H7O6P
Molar mass 170.058
 N (verify) (what is: Y/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Glyceraldehyde 3-phosphate, also known as triose phosphate or 3-phosphoglyceraldehyde and abbreviated as G3P, GADP, GAP, TP, GALP or PGAL, is a chemical compound that occurs as an intermediate in several central metabolic pathways of all organisms. It is a phosphate ester of the 3-carbon sugar glyceraldehyde and has chemical formula C3H7O6P.

The CAS number of glyceraldehyde 3-phosphate is 142-10-9 and that of D-glyceraldehyde 3-phosphate (one of the two optical isomers of the compound and the one most often occurring in living organisms) is 591-57-1.

Contents

An intermediate in both glycolysis and gluconeogenesis

Formation

D-glyceraldehyde 3-phosphate is formed from the following three compounds in reversible reactions:

β-D-fructose 1,6-bisphosphate fructose bisphosphate aldolase D-glyceraldehyde 3-phosphate dihydroxyacetone phosphate
+
fructose bisphosphate aldolase

Compound C05378 at KEGG Pathway Database. Enzyme 4.1.2.13 at KEGG Pathway Database. Compound C00111 at KEGG Pathway Database. Compound C00118 at KEGG Pathway Database.

The numbering of the carbon atoms indicates the fate of the carbons according to their position in fructose 6-phosphate.

Dihydroxyacetone phosphate triose phosphate isomerase D-glyceraldehyde 3-phosphate
 
 
  triose phosphate isomerase

Compound C00111 at KEGG Pathway Database.Enzyme 5.3.1.1 at KEGG Pathway Database.Compound C00118 at KEGG Pathway Database.

As a substrate

glyceraldehyde 3-phosphate glyceraldehyde phosphate dehydrogenase D-glycerate 1,3-bisphosphate
 
NAD+ + Pi NADH + H+
NAD+ + Pi NADH + H+
 
 

Compound C00118 at KEGG Pathway Database. Enzyme 1.2.1.12 at KEGG Pathway Database. Reaction R01063 at KEGG Pathway Database. Compound C00236 at KEGG Pathway Database.

D-glyceraldehyde 3-phosphate is also of some importance since this is how glycerol (as DHAP) enters the glycolytic and gluconeogenic pathways. Furthermore, it is a participant in and a product of the pentose phosphate pathway.

An intermediate in photosynthesis

During plant photosynthesis, 2 molecules of glycerate 3-phosphate (GP; also known as 3-phosphoglycerate) are produced by the first step of the light-independent reactions when ribulose 1,5-bisphosphate (RuBP) and carbon dioxide are catalysed by the rubisco enzyme. The GP is converted to D-glyceraldehyde 3-phosphate (G3P) using the energy in ATP and the reducing power of NADPH as part of the Calvin cycle. This returns ADP, phosphate ions Pi, and NADP+ to the light-dependent reactions of photosynthesis for their continued function. RuBP is regenerated for the Calvin cycle to continue.

G3P is generally considered the prime end-product of photosynthesis and it can be used as an immediate food nutrient, combined and rearranged to form monosaccharide sugars, such as glucose, which can be transported to other cells, or packaged for storage as insoluble polysaccharides such as starch.

Balance sheet

6 CO2 + 6 RuBP (+ energy from 12 ATP and 12 NADPH) →12 G3P (3-carbon)

10 G3P (+ energy from 6 ATP) → 6 RuBP (i.e. starting material regenerated)

2 G3Pglucose (6-carbon).

In tryptophan biosynthesis

Glyceraldehyde 3-phosphate occurs as a byproduct in the biosynthesis pathway of tryptophan, an essential amino acid that cannot be produced by the human body.

In thiamine biosynthesis

Glyceraldehyde 3-phosphate occurs as a reactant in the biosynthesis pathway of thiamine (Vitamin B1), another substance that cannot be produced by the human body.

External links