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6-Phosphogluconic Acid
6-Phosphogluconic acid (6-phosphogluconate) is an intermediate in the pentose phosphate pathway and the Entner–Doudoroff pathway. It is formed by 6-phosphogluconolactonase, and acted upon by phosphogluconate dehydrogenase to produce ribulose 5-phosphate Ribulose 5-phosphate is one of the end-products of the pentose phosphate pathway. It is also an intermediate in the Calvin cycle The Calvin cycle, light-independent reactions, bio synthetic phase, dark reactions, or photosynthetic carbon reducti .... It may also be acted upon by 6- phosphogluconate dehydratase to produce 2-keto-3-deoxy-6-phosphogluconate. Organophosphates {{biochem-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pentose Phosphate Pathway
The pentose phosphate pathway (also called the phosphogluconate pathway and the hexose monophosphate shunt and the HMP Shunt) is a metabolic pathway parallel to glycolysis. It generates NADPH and pentoses (5-carbon sugars) as well as ribose 5-phosphate, a precursor for the synthesis of nucleotides. While the pentose phosphate pathway does involve oxidation of glucose, its primary role is anabolic rather than catabolic. The pathway is especially important in red blood cells (erythrocytes). There are two distinct phases in the pathway. The first is the oxidative phase, in which NADPH is generated, and the second is the non-oxidative synthesis of 5-carbon sugars. For most organisms, the pentose phosphate pathway takes place in the cytosol; in plants, most steps take place in plastids. Like glycolysis, the pentose phosphate pathway appears to have a very ancient evolutionary origin. The reactions of this pathway are mostly enzyme-catalyzed in modern cells, however, they also occur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Entner–Doudoroff Pathway
The Entner–Doudoroff pathway (ED Pathway) is a metabolic pathway that is most notable in Gram-negative bacteria, certain Gram-positive bacteria and archaea. Glucose is the substrate in the ED pathway and through a series of enzyme assisted chemical reactions it is catabolized into pyruvate. Entner and Doudoroff (1952) and MacGee and Doudoroff (1954) first reported the ED pathway in the bacterium '' Pseudomonas saccharophila''. While originally thought to be just an alternative to glycolysis (EMP) and the pentose phosphate pathway (PPP), some studies now suggest that the original role of the EMP may have originally been about anabolism and repurposed over time to catabolism, meaning the ED pathway may be the older pathway. Recent studies have also shown the prevalence of the ED pathway may be more widespread than first predicted with evidence supporting the presence of the pathway in cyanobacteria, ferns, algae, mosses, and plants.Chen, Xi, et al. "The Entner–Doudoroff pat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
6-phosphogluconolactonase
6-Phosphogluconolactonase (EC 3.1.1.31, 6PGL, PGLS, systematic name 6-phospho-D-glucono-1,5-lactone lactonohydrolase) is a cytosolic enzyme found in all organisms that catalyzes the hydrolysis of 6-phosphogluconolactone to 6-phosphogluconic acid in the oxidative phase of the pentose phosphate pathway: :6-phospho-D-glucono-1,5-lactone + H2O = 6-phospho-D-gluconate The tertiary structure of 6PGL employs an α/β hydrolase fold, with active site residues clustered on the loops of the α-helices. Based on the crystal structure of the enzyme, the mechanism is proposed to be dependent on proton transfer by a histidine residue in the active site. 6PGL selectively catalyzes the hydrolysis of δ-6-phosphogluconolactone, and has no activity on the γ isomer. Enzyme Mechanism 6PGL hydrolysis of 6-phosphogluconolactone to 6-phosphogluconic acid has been proposed to proceed via proton transfer to the O5 ring oxygen atom, similar to xylose isomerase and ribose-5-phosphate isomerase. The r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphogluconate Dehydrogenase
6-Phosphogluconate dehydrogenase (6PGD) is an enzyme in the pentose phosphate pathway. It forms ribulose 5-phosphate from 6-phosphogluconate: :6-phospho-D-gluconate + NAD(P)+ \rightleftharpoons D-Ribulose 5-phosphate + CO2 + NAD(P)H + H+ It is an oxidative carboxylase that catalyses the decarboxylating reduction of 6-phosphogluconate into ribulose 5-phosphate in the presence of NADP. This reaction is a component of the hexose mono-phosphate shunt and pentose phosphate pathways (PPP). Prokaryotic and eukaryotic 6PGD are proteins of about 470 amino acids whose sequences are highly conserved. The protein is a homodimer in which the monomers act independently: each contains a large, mainly alpha-helical domain and a smaller beta-alpha-beta domain, containing a mixed parallel and anti-parallel 6-stranded beta sheet. NADP is bound in a cleft in the small domain, the substrate binding in an adjacent pocket. Biotechnological significance Recently, 6PGD was demonstrated to cata ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ribulose 5-phosphate
Ribulose 5-phosphate is one of the end-products of the pentose phosphate pathway. It is also an intermediate in the Calvin cycle. It is formed by phosphogluconate dehydrogenase, and it can be acted upon by phosphopentose isomerase and phosphopentose epimerase. In plants, Ribulose 5-phosphate produced from the pentose-phosphate pathway is converted into Ribulose-1-5-bisphosphate by the enzyme phosphoribokinase. See also * Ribulose * Ribulose-1,5-bisphosphate Ribulose 1,5-bisphosphate (RuBP) is an organic substance that is involved in photosynthesis, notably as the principal acceptor in plants. It is a colourless anion, a double phosphate ester of the ketopentose (ketone-containing sugar with five car ... Organophosphates Monosaccharide derivatives {{biochem-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphogluconate Dehydratase
The enzyme phosphogluconate dehydratase () catalyzes the chemical reaction :6-phospho-D-gluconate \rightleftharpoons 2-dehydro-3-deoxy-6-phospho-D-gluconate + H2O This enzyme belongs to the family of lyases, specifically the hydro-lyases, which cleave carbon-oxygen bonds. The systematic name of this enzyme class is 6-phospho-D-gluconate hydro-lyase (2-dehydro-3-deoxy-6-phospho-D-gluconate-forming). Other names in common use include 6-phosphogluconate dehydratase, 6-phosphogluconic dehydrase, gluconate-6-phosphate dehydratase, gluconate 6-phosphate dehydratase, 6-phosphogluconate dehydrase, and 6-phospho-Dgluconate hydro-lyase. This enzyme participates in the Entner–Doudoroff pathway. Structural studies As of late 2007, only one structure A structure is an arrangement and organization of interrelated elements in a material object or system, or the object or system so organized. Material structures include man-made objects such as buildings and machines and natural objects ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
