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Ribose-5-phosphate
Ribose 5-phosphate (R5P) is both a product and an intermediate of the pentose phosphate pathway. The last step of the oxidative reactions in the pentose phosphate pathway is the production of ribulose 5-phosphate. Depending on the body's state, ribulose 5-phosphate can reversibly isomerize to ribose 5-phosphate. Ribulose 5-phosphate can alternatively undergo a series of isomerizations as well as transaldolations and transketolations that result in the production of other pentose phosphates as well as fructose 6-phosphate and glyceraldehyde 3-phosphate (both intermediates in glycolysis). The enzyme ribose-phosphate diphosphokinase converts ribose-5-phosphate into phosphoribosyl pyrophosphate. Structure R5P consists of a five-carbon sugar, ribose, and a phosphate group at the five-position carbon. It can exist in open chain form or in furanose form. The furanose form is most commonly referred to as ribose 5-phosphoric acid. Biosynthesis The formation of R5P is highly depen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ribose-5-phosphate Isomerase
Ribose-5-phosphate isomerase (Rpi) encoded by the RPIA gene is an enzyme () that catalyzes the conversion between ribose-5-phosphate (R5P) and ribulose-5-phosphate (Ru5P). It is a member of a larger class of isomerases which catalyze the interconversion of chemical isomers (in this case structural isomers of pentose). It plays a vital role in biochemical metabolism in both the pentose phosphate pathway and the Calvin cycle. The systematic name of this enzyme class is D-ribose-5-phosphate aldose-ketose-isomerase. Structure Gene RpiA in human beings is encoded on the second chromosome on the short arm (p arm) at position 11.2. Its encoding sequence is nearly 60,000 base pairs long. The only known naturally occurring genetic mutation results in ribose-5-phosphate isomerase deficiency, discussed below. The enzyme is thought to have been present for most of evolutionary history. Knock-out experiments conducted on the genes of various species meant to encode RpiA have indicated simi ... [...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 or HMP shunt) is a metabolic pathway parallel to glycolysis. It generates NADPH and pentoses (five-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). The reactions of the pathway were elucidated in the early 1950s by Bernard Horecker and co-workers. 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 five-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 ori ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ribose
Ribose is a simple sugar and carbohydrate with molecular formula C5H10O5 and the linear-form composition H−(C=O)−(CHOH)4−H. The naturally occurring form, , is a component of the ribonucleotides from which RNA is built, and so this compound is necessary for coding, decoding, regulation and expression of genes. It has a structural analog, deoxyribose, which is a similarly essential component of DNA. is an unnatural sugar that was first prepared by Emil Fischer and Oscar Piloty in 1891. It was not until 1909 that Phoebus Levene and Walter Jacobs recognised that was a natural product, the enantiomer of Fischer and Piloty's product, and an essential component of nucleic acids. Fischer chose the name "ribose" as it is a partial rearrangement of the name of another sugar, arabinose, of which ribose is an epimer at the 2' carbon; both names also relate to gum arabic, from which arabinose was first isolated and from which they prepared . Like most sugars, ribo ... [...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 in the pentose phosphate pathway. Ribulose 5-phosphate is involved in various metabolic pathways. Ribulose 5-phosphate can be acted upon by phosphopentose isomerase to form ribose 5-phosphate Ribose 5-phosphate (R5P) is both a product and an intermediate of the pentose phosphate pathway. The last step of the oxidative reactions in the pentose phosphate pathway is the production of ribulose 5-phosphate. Depending on the body's state, ..., which is a precursor for nucleotide and co-factor biosynthesis. Ribulose-5 phosphate can also be acted upon by phosphopentose epimerase to form xylulose 5-phosphate, which is used in the nonoxidative phase of the pentose phosphate pathway in humans to generate precursor molecules for the synthesis of aromatic amino acids and production of energy. In plants, ribulose ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transketolase
Transketolase (abbreviated as TK) is an enzyme that, in humans, is encoded by the ''TKT'' gene. It participates in both the pentose phosphate pathway in all organisms and the Calvin cycle of photosynthesis. Transketolase catalyzes two important reactions, which operate in opposite directions in these two pathways. In the first reaction of the non-oxidative pentose phosphate pathway, the cofactor thiamine diphosphate accepts a 2-carbon fragment from a 5-carbon ketose (D-xylulose-5-P), then transfers this fragment to a 5-carbon aldose (D-ribose-5-P) to form a 7-carbon ketose (sedoheptulose-7-P). The abstraction of two carbons from D-xylulose-5-P yields the 3-carbon aldose glyceraldehyde-3-P. In the Calvin cycle, transketolase catalyzes the reverse reaction, the conversion of sedoheptulose-7-P and glyceraldehyde-3-P to pentoses, the aldose D-ribose-5-P and the ketose D-xylulose-5-P. The second reaction catalyzed by transketolase in the pentose phosphate pathway involves the same thia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conversion
Conversion or convert may refer to: Arts, entertainment, and media * ''The Convert'', a 2023 film produced by Jump Film & Television and Brouhaha Entertainment * "Conversion" (''Doctor Who'' audio), an episode of the audio drama ''Cyberman'' * "Conversion" (''Stargate Atlantis''), an episode of the television series ''Stargate Atlantis'' * "The Conversion" (''The Outer Limits''), a 1995 episode of the television series ''The Outer Limits'' * " Chapter 19: The Convert", an episode of the television series ''The Mandalorian'' Business and marketing * Conversion funnel, the path a consumer takes through the web toward or near a desired action or conversion * Conversion marketing, when a website's visitors take a desired action * Converting timber to commercial lumber Computing, science, and technology * Conversion of units, conversion between different units of measurement Computing and telecommunication * CHS conversion of data storage, mapping cylinder/head/sector tuples ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyruvate Kinase
Pyruvate kinase is the enzyme involved in the last step of glycolysis. It catalyzes the transfer of a phosphate group from phosphoenolpyruvate (PEP) to adenosine diphosphate (ADP), yielding one molecule of pyruvate and one molecule of ATP. Pyruvate kinase was inappropriately named (inconsistently with a conventional kinase) before it was recognized that it did not directly catalyze phosphorylation of pyruvate, which does not occur under physiological conditions. Pyruvate kinase is present in four distinct, tissue-specific isozymes in animals, each consisting of particular kinetic properties necessary to accommodate the variations in metabolic requirements of diverse tissues. Isozymes in vertebrates Four isozymes of pyruvate kinase expressed in vertebrates: L (liver), R (erythrocytes), M1 (muscle and brain) and M2 (early fetal tissue and most adult tissues). The L and R isozymes are expressed by the gene PKLR, whereas the M1 and M2 isozymes are expressed by the gene PKM2. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transaldolase
Transaldolase is an enzyme () of the non-oxidative phase of the pentose phosphate pathway. In humans, transaldolase is encoded by the ''TALDO1'' gene. The following chemical reaction is catalyzed by transaldolase: : sedoheptulose 7-phosphate + glyceraldehyde 3-phosphate \rightleftharpoons erythrose 4-phosphate + fructose 6-phosphate Clinical significance The pentose phosphate pathway has two metabolic functions: (1) generation of nicotinamide adenine dinucleotide phosphate (reduced NADPH), for reductive biosynthesis, and (2) formation of ribose, which is an essential component of ATP, DNA, and RNA. Transaldolase links the pentose phosphate pathway to glycolysis. In patients with deficiency of transaldolase, there's an accumulation of erythritol (from erythrose 4-phosphate), D-arabitol, and ribitol. The deletion in 3 base pairs in the ''TALDO1'' gene results in the absence of serine at position 171 of the transaldolase protein, which is part of a highly conserved region, s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glyceraldehyde 3-phosphate
Glyceraldehyde 3-phosphate, also known as triose phosphate or 3-phosphoglyceraldehyde and abbreviated as G3P, GA3P, GADP, GAP, TP, GALP or PGAL, is a metabolite that occurs as an intermediate in several central pathways of all organisms.Nelson, D. L.; Cox, M. M. "Lehninger, Principles of Biochemistry" 3rd Ed. Worth Publishing: New York, 2000. . With the chemical formula H(O)CCH(OH)CH2OPO32-, this anion is a monophosphate ester of glyceraldehyde. An intermediate in both glycolysis and gluconeogenesis Formation D-glyceraldehyde 3-phosphate is formed from the following three compounds in reversible reactions: * Fructose-1,6-bisphosphate ( F1,6BP), catalyzed by aldolase. ''The numbering of the carbon atoms indicates the fate of the carbons according to their position in fructose 6-phosphate.'' * Dihydroxyacetone phosphate ( DHAP), catalyzed by triose phosphate isomerase. * 1,3-bisphosphoglycerate ( 1,3BPG), catalyzed by glyceraldehyde 3-phosphate dehydrogenase. As a subst ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fructose 6-phosphate
Fructose 6-phosphate (sometimes called the Neuberg ester) is a derivative of fructose, which has been phosphorylated at the 6-hydroxy group. It is one of several possible fructosephosphates. The β-D-form of this compound is very common in cells. The great majority of glucose is converted to fructose 6-phosphate upon entering a cell. Fructose is predominantly converted to fructose 1-phosphate by fructokinase following cellular import. History The name ''Neuberg ester'' comes from the German biochemist Carl Neuberg. In 1918, he found that the compound (later identified as fructose 6-phosphate) was produced by mild acid hydrolysis of fructose 2,6-bisphosphate.Fruton, Joseph S. ''Proteins, Enzymes, Genes: The Interplay of Chemistry and Biology''. Yale University Press: New Haven, 1999. p 292 In glycolysis Fructose 6-phosphate lies within the glycolysis metabolic pathway and is produced by isomerisation of glucose 6-phosphate Glucose 6-phosphate (G6P, sometimes called the Ro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycolysis
Glycolysis is the metabolic pathway that converts glucose () into pyruvic acid, pyruvate and, in most organisms, occurs in the liquid part of cells (the cytosol). The Thermodynamic free energy, free energy released in this process is used to form the high-energy molecules adenosine triphosphate (ATP) and NADH, reduced nicotinamide adenine dinucleotide (NADH). Glycolysis is a sequence of ten reactions catalyzed by enzymes. The wide occurrence of glycolysis in other species indicates that it is an ancient metabolic pathway. Indeed, the reactions that make up glycolysis and its parallel pathway, the pentose phosphate pathway, can occur in the Great Oxygenation Event, oxygen-free conditions of the Archean oceans, also in the absence of enzymes, catalyzed by metal ions, meaning this is a plausible prebiotic pathway for abiogenesis. The most common type of glycolysis is the ''Embden–Meyerhof–Parnas (EMP) pathway'', which was discovered by Gustav Embden, Otto Meyerhof, and Jakub Kar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
