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Shikimate
Shikimic acid, more commonly known as its anionic form shikimate, is a cyclohexene, a cyclitol and a cyclohexanecarboxylic acid. It is an important biochemical metabolite in plants and microorganisms. Its name comes from the Japanese flower ''shikimi'' (, the Japanese star anise, ''Illicium anisatum''), from which it was first isolated in 1885 by Johan Fredrik Eykman. The elucidation of its structure was made nearly 50 years later. Biosynthesis Phosphoenolpyruvate and erythrose-4-phosphate condense to form 3-deoxy-D-arabinoheptulosonate-7-phosphate (DAHP), in a reaction catalyzed by the enzyme DAHP synthase. DAHP is then transformed to 3-dehydroquinate (DHQ), in a reaction catalyzed by DHQ synthase. Although this reaction requires nicotinamide adenine dinucleotide (NAD) as a cofactor, the enzymic mechanism regenerates it, resulting in the net use of no NAD. : DHQ is dehydrated to 3-dehydroshikimic acid by the enzyme 3-dehydroquinate dehydratase, which is reduced to shi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shikimate Dehydrogenase
In enzymology, a shikimate dehydrogenase () is an enzyme that catalyzes the chemical reaction :shikimate + NADP+ \rightleftharpoons 3-dehydroshikimate + NADPH + H+ Thus, the two substrates of this enzyme are shikimate and NADP+, whereas its 3 products are 3-dehydroshikimate, NADPH, and H+. This enzyme participates in phenylalanine, tyrosine and tryptophan biosynthesis. Function Shikimate dehydrogenase is an enzyme that catalyzes one step of the shikimate pathway. This pathway is found in bacteria, plants, fungi, algae, and parasites and is responsible for the biosynthesis of aromatic amino acids (phenylalanine, tyrosine, and tryptophan) from the metabolism of carbohydrates. In contrast, animals and humans lack this pathway hence products of this biosynthetic route are essential amino acids that must be obtained through an animal's diet. There are seven enzymes that play a role in this pathway. Shikimate dehydrogenase (also known as 3-dehydroshikimate dehydrogenase) is t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shikimate Pathway 1
Shikimic acid, more commonly known as its anionic form shikimate, is a cyclohexene, a cyclitol and a cyclohexanecarboxylic acid. It is an important biochemical metabolite in plants and microorganisms. Its name comes from the Japanese flower ''shikimi'' (, the Japanese star anise, ''Illicium anisatum''), from which it was first isolated in 1885 by Johan Fredrik Eykman. The elucidation of its structure was made nearly 50 years later. Biosynthesis Phosphoenolpyruvate and erythrose-4-phosphate condense to form 3-deoxy-D-arabinoheptulosonate-7-phosphate (DAHP), in a reaction catalyzed by the enzyme DAHP synthase. DAHP is then transformed to 3-dehydroquinate (DHQ), in a reaction catalyzed by DHQ synthase. Although this reaction requires nicotinamide adenine dinucleotide (NAD) as a cofactor, the enzymic mechanism regenerates it, resulting in the net use of no NAD. : DHQ is dehydrated to 3-dehydroshikimic acid by the enzyme 3-dehydroquinate dehydratase, which is reduced to shikimi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shikimate Pathway 2
Shikimic acid, more commonly known as its anionic form shikimate, is a cyclohexene, a cyclitol and a cyclohexanecarboxylic acid. It is an important biochemical metabolite in plants and microorganisms. Its name comes from the Japanese flower ''shikimi'' (, the Japanese star anise, ''Illicium anisatum''), from which it was first isolated in 1885 by Johan Fredrik Eykman. The elucidation of its structure was made nearly 50 years later. Biosynthesis Phosphoenolpyruvate and erythrose-4-phosphate condense to form 3-deoxy-D-arabinoheptulosonate-7-phosphate (DAHP), in a reaction catalyzed by the enzyme DAHP synthase. DAHP is then transformed to 3-dehydroquinate (DHQ), in a reaction catalyzed by DHQ synthase. Although this reaction requires nicotinamide adenine dinucleotide (NAD) as a cofactor, the enzymic mechanism regenerates it, resulting in the net use of no NAD. : DHQ is dehydrated to 3-dehydroshikimic acid by the enzyme 3-dehydroquinate dehydratase, which is reduced to shikimi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shikimate Kinase
Shikimate kinase () is an enzyme that catalyzes the ATP-dependent phosphorylation of shikimate to form shikimate 3-phosphate. This reaction is the fifth step of the shikimate pathway, which is used by plants and bacteria to synthesize the common precursor of aromatic amino acids and secondary metabolites. The systematic name of this enzyme class is ATP:shikimate 3-phosphotransferase. Other names in common use include shikimate kinase (phosphorylating), and shikimate kinase II. Background The shikimate pathway consists of seven enzymatic reactions by which phosphoenolpyruvate and erythrose 4-phosphate are converted to chorismate, the common precursor of the aromatic amino acids phenylalanine, tyrosine, and tryptophan. The aromatic amino acids are used in the synthesis of proteins and, in plants, fungi, and bacteria, give rise to a number of other specialized metabolites, such as phenylpropanoids and alkaloids. Chorismate and several other intermediates of the pathway serve as prec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aromatic Amino Acid
An aromatic amino acid is an amino acid that includes an aromatic ring. Among the 20 standard amino acids, the following are classically considered aromatic: phenylalanine, tryptophan and tyrosine. Although histidine contains an aromatic ring, its basic properties cause it to be predominantly classified as a polar amino acid. Chemical structure and properties Aromatic amino acids absorb ultraviolet light at a wavelength above 250 nm and produce fluorescence. This characteristic is used in quantitative analysis, notably in determining the concentrations of these amino acids in solution. This achieved through the utilization of a UV spectrophotomer and the Beer-Lambert Law equation. Most proteins will have an absorption maximum at 280 nm due to the presence of aromatic amino acids in their primary structure. However, because several aromatic amino acids exist, this method has low accuracy; in order to mitigate this issue, the desired protein must be pure, and its molar absorp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
3-dehydroquinate Dehydratase
The enzyme 3-dehydroquinate dehydratase () catalyzes the chemical reaction :3-dehydroquinate \rightleftharpoons 3-dehydroshikimate + H2O This enzyme belongs to the family of lyases, specifically the hydro-lyases, which cleave carbon-oxygen bonds. This enzyme participates in phenylalanine, tyrosine and tryptophan biosynthesis. Discovery The shikimate pathway was determined to be a major biosynthetic route for the production of aromatic amino acids through the research of Bernhard Davis and David Sprinson. Role in the shikimate pathway 3-Dehydroquinate Dehydratase is an enzyme that catalyzes the third step of the shikimate pathway. The shikimate pathway is a biosynthetic pathway that allows plants, fungi, and bacteria to produce aromatic amino acids. Mammals do not have this pathway, meaning that they must obtain these essential amino acids through their diet. Aromatic Amino acids include Phenylalanine, Tyrosine, and Tryptophan. This enzyme dehydrates 3-Dehydroquinate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chorismate Synthase
The enzyme chorismate synthase (EC 4.2.3.5) catalyzes the chemical reaction :5-''O''-(1-carboxyvinyl)-3-phosphoshikimate \rightleftharpoons chorismate + phosphate This enzyme belongs to the family of lyases, specifically those carbon-oxygen lyases acting on phosphates. The systematic name of this enzyme class is 5-''O''-(1-carboxyvinyl)-3-phosphoshikimate phosphate-lyase (chorismate-forming). This enzyme is also called 5-''O''-(1-carboxyvinyl)-3-phosphoshikimate phosphate-lyase. This enzyme participates in phenylalanine, tyrosine and tryptophan biosynthesis. Chorismate synthase catalyzes the last of the seven steps in the shikimate pathway which is used in prokaryotes, fungi and plants for the biosynthesis of aromatic amino acids. It catalyzes the 1,4-trans elimination of the phosphate group from 5-enolpyruvylshikimate-3-phosphate (EPSP) to form chorismate which can then be used in phenylalanine, tyrosine or tryptophan biosynthesis. Chorismate synthase requires the presenc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DAHP Synthase
3-Deoxy-D-arabinoheptulosonate 7-phosphate (DAHP) synthase () is the first enzyme in a series of metabolic reactions known as the shikimate pathway, which is responsible for the biosynthesis of the amino acids phenylalanine, tyrosine, and tryptophan. Since it is the first enzyme in the shikimate pathway, it controls the amount of carbon entering the pathway. Enzyme inhibition is the primary method of regulating the amount of carbon entering the pathway. Forms of this enzyme differ between organisms, but can be considered DAHP synthase based upon the reaction that is catalyzed by this enzyme. In enzymology, a DAHP synthase () is an enzyme that catalyzes the chemical reaction :phosphoenolpyruvate + D-erythrose 4-phosphate + H2O \rightleftharpoons 3-deoxy-D-arabino-hept-2-ulosonate 7-phosphate + phosphate The three substrates of this enzyme are phosphoenolpyruvate, D-erythrose 4-phosphate, and H2O, whereas its two products are 3-deoxy-D-arabino-hept-2-ulosonate 7-phosphate and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
3-Dehydroquinic Acid
3-Dehydroquinic acid (DHQ) is the first carbocyclic intermediate of the shikimate pathway. It is created from 3-deoxyarabinoheptulosonate 7-phosphate, a 7-carbon ulonic acid, by the enzyme DHQ synthase. The mechanism of ring closure is complex, but involves an aldol condensation at C-2 and C-7. It has the same structure as quinic acid, which is found in coffee, but the C-3 hydroxyl is oxidized to a ketone group. 3-Dehydroquinic acid undergoes five further enzymatic steps in the remainder of the shikimate pathway to chorismic acid, a precursor to tyrosine, 3-phenylalanine, tryptophan, and some vitamins, including: * Vitamin K * Pteroylmonoglutamic acid, called folate. 3-Dehydroquinate can also be a precursor to pyrroloquinoline quinone (PQQ), an alternate redox coenzyme involved in oxidative phosphorylation. Biosynthesis 3-Dehydroquinate goes through beta oxidation, similar to fatty acids. Then, this compound (6-oxo-3-dehydro-quinate) is transaminated to 6-amino-3-dehydroquin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
EPSP Synthase
5-enolpyruvylshikimate-3-phosphate (EPSP) synthase is an enzyme produced by plants and microorganisms. EPSPS catalyzes the chemical reaction: : phosphoenolpyruvate (PEP) + 3-phospho shikimate (S3P) phosphate + 5-enolpyruvylshikimate-3-phosphate (EPSP) Thus, the two substrates of this enzyme are phosphoenolpyruvate (PEP) and 3-phosphoshikimate, whereas its two products are phosphate and 5-enolpyruvylshikimate-3-phosphate. This enzyme is not present in animals. It presents an attractive biological target for herbicides, such as glyphosate. A glyphosate-resistant version of this gene has been used in genetically modified crops. Nomenclature The enzyme belongs to the family of transferases, to be specific those transferring aryl or alkyl groups other than methyl groups. The systematic name of this enzyme class is phosphoenolpyruvate:3-phosphoshikimate 5-''O''-(1-carboxyvinyl)-transferase. Other names in common use include: * 5-enolpyruvylshikimate-3-phosphate synthase, * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
3-dehydroquinate Synthase
The enzyme 3-dehydroquinate synthase (EC 4.2.3.4) catalyzes the chemical reaction : 3-deoxy-D-''arabino''-hept-2-ulosonate 7-phosphate \rightleftharpoons 3-dehydroquinate + phosphate The protein uses NAD+ to catalyze the reaction. This reaction is part of the shikimate pathway which is involved in the biosynthesis of aromatic amino acids. 3-Dehydroquinate synthase belongs to the family of lyases, to be specific those carbon-oxygen lyases acting on phosphates. This enzyme participates in phenylalanine, tyrosine, and tryptophan biosynthesis. It employs one cofactor, cobalt (Co2+). Background The shikimate pathway is composed of seven steps, each catalyzed by an enzyme. The shikimate pathway is responsible for producing the precursors for aromatic amino acids, which are essential to our diets because we cannot synthesize them in our bodies. Only plants, bacteria, and microbial eukaryotes are capable of producing aromatic amino acids. The pathway ultimately converts phospho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenylalanine
Phenylalanine (symbol Phe or F) is an essential α-amino acid with the formula . It can be viewed as a benzyl group substituted for the methyl group of alanine, or a phenyl group in place of a terminal hydrogen of alanine. This essential amino acid is classified as neutral, and nonpolar because of the inert and hydrophobic nature of the benzyl side chain. The L-isomer is used to biochemically form proteins coded for by DNA. Phenylalanine is a precursor for tyrosine, the monoamine neurotransmitters dopamine, norepinephrine (noradrenaline), and epinephrine (adrenaline), and the skin pigment melanin. It is encoded by the codons UUU and UUC. Phenylalanine is found naturally in the milk of mammals. It is used in the manufacture of food and drink products and sold as a nutritional supplement for its analgesic and antidepressant effects. It is a direct precursor to the neuromodulator phenethylamine, a commonly used dietary supplement. As an essential amino acid, phenylalanine is n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
