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Introduction:

1.Class of enzymes: oxidoreductase. In biochemistry, an oxidoreductase is an enzyme that catalyzes the transfer of electrons from one molecule (the reductant, also called the hydrogen or electron donor) to another (the oxidant, also called the hydrogen or electron acceptor). This group of enzymes usually utilizes NADP or NAD as cofactors.

2.Glyceraldehyde 3-phosphate dehydrogenase (abbreviated as GAPDH or less commonly as G3PDH) (EC 1.2.1.12) is an enzyme of ~37kDa that catalyzes the sixth step of glycolysis and thus serves to break down glucose for energy and carbon molecules. In addition to this long established metabolic function, GAPDH has recently been implicated in several non-metabolic processes, including transcription activation, initiation of apoptosis,[1] and ER to Golgi vesicle shuttling.

3.Aerobic organisms. Humans. Found in eubacteria and eukaryotes. Electrophoretically distinct forms of glyceraldehyde-3-phosphate dehydrogenase (TDH) (threonine dehydrogenase) have been detected in turtle, perch, trout, spinach, and yeast. Glyceraldehyde 3-phosphate dehydrogenases (GAPDHs) are cytoplasmic glycolytic enzymes, which although lacking identifiable secretion signals, have also been found localized to the surface of several bacteria (and some eukaryotic organisms); where in some cases they have been shown to contribute to the colonization and invasion of host tissues. Two very different types of phosphorylating GAPDH enzymes with only 10% to 15% sequence similarity are distributed across eubacteria and archaebacteria; these were designated as class I and class II GAPDH (Cerff 1995). Whereas class II GAPDH has so far only been found in archaebacteria (Hensel et al. 1989), class I GAPDH is the classic enzyme of glycolysis and the Calvin cycle in eubacteria and eukaryotes and has been characterized in one halophilic archaebacterium. http://mbe.oxfordjournals.org/content/16/4/429.full.pdf

4.Glyceraldehyde-3-phosphate dehydrogenase deficiency: A rare genetic syndrome characterized by a deficiency of an enzyme (Glyceraldehyde-3-phosphate dehydrogenase) which is involved in breaking down carbohydrates consumed in the diet in order to produce energy. Asymptomatic. http://www.jstor.org/stable/40537793 In plants, glycolysis occurs in both the cytosol and the plastids. In a chloroplast/plastid-localized GAPDH isoform, gapcp, these double mutants have displayed a drastic phenotype of arrested root development, dwarfism, and sterility.

Ligand and Interaction- (From PDB): NAD and (depending on what organic the enzyme is isolated from). Length: 334

For homo sapien species, ligands are : ASO, EDO, MN, and UDP.

Inhibitors

In the course of a study on the oxidation of various aldehydes by glyceraldehyde 3-phosphate dehydrogenase (l), it was observed that aged preparations of glycolaldehyde 2-phosphate inhibited strongly the activity of glyceraldehyde Q-phosphate dehydrogenase. Differences in inhibitory potency of several orders of magnitude were noted between various batches. Inhibition of Glyceraldehyde S-P Dehydrogenase by Tetrose di-P -Very low concentrations of tetrose di-P inhibited the oxidation of giyceraldehyde-3-P, as shown in Table II. After treatment with potato phosphatase, over 99% of the inhibitory action was lost. Freshly prepared solutions of glycolaldehyde-2-P, n-erythrose- 4-P, and ribulose di-P were also comparatively ineffective. On the other hand n-threose-2,4-di-P was found to be a more potent inhibitor than the mixture of tetrose di-P isomers.2 As shown in Table II, the oxidation of glyceraldehyde by glyceraldehyde-3-P dehydrogenase was also inhibited by tetros edi-P. Since the rate of glyceraldehyde oxidation is slow, large amounts of enzyme were used, and more tetrose di-P was required to produce inhibition than necessary for glyceraldehyde- 3-P oxidation. Tetrose di-P had no effect on alcohol and lactate dehydrogenase. Aldolase, transaldolase, and transketolase enzymes, known to act on erythrose-4-P, were not inhibited at low concentrations of tetrose di-P. http://www.jbc.org/content/234/10/2510.full.pdf

Pentalenolactone (PL), an antibiotic produced by several strains of Streptomycetes, is a specific irreversible inhibitor of glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.12). The effect of this antibiotic was studied in Trypanosoma brucei. In infected mice, due to the rapid metabolic inactivation of PL in vivo, trypanosomes were not affected by concentrations that were lethal to the host. Bloodstream trypanosomes in vitro were killed by low concentrations of PL (1.5 μg ml−1), suggesting that there is no alternative to the glycolytic pathway for the generation of ATP in the bloodstream forms. In contrast, even high concentrations of PL (75 μg ml−1) were unable to inhibit growth of the procyclic form in vitro, presumably due to their ability to generate ATP independently of the glycolytic pathway.