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| {{enzyme
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| | Name = 3-deoxy-7-phosphoheptulonate synthase
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| | EC_number = 2.5.1.54
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| | CAS_number = 9026-94-2
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| | IUBMB_EC_number = 2/5/1/54
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| | GO_code = 0003849
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| | image =
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| {{Infobox protein family
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| | Symbol = DAHP_synth_1
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| | Name = DAHP synthetase I domain
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| | image = PDB 1pck EBI.jpg
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| | width =
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| | caption = Structure of ''Aquifex aeolicus kdo8ps'' in complex with z-methyl-pep 2-dehydro-3-deoxyphosphooctonate aldolase.<ref name="pmid14675946">{{cite journal| author=Xu X, Wang J, Grison C, Petek S, Coutrot P, Birck MR et al.| title=Structure-based design of novel inhibitors of 3-deoxy-D-manno-octulosonate 8-phosphate synthase. | journal=Drug Des Discov | year= 2003 | volume= 18 | issue= 2-3 | pages= 91–9 | pmid=14675946 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=14675946 }}</ref>
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| | Pfam = PF00793
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| | Pfam_clan = CL0036
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| | InterPro = IPR006218
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| | SMART =
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| | PROSITE =
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| | MEROPS =
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| | SCOP = 51569
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| | TCDB =
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| | OPM family =
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| | OPM protein =
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| | CDD =
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| '''3-Deoxy-D-arabinoheptulosonate 7-phosphate (DAHP) synthase''' ({{EC number|2.5.1.54}}) is the first enzyme in a series of [[metabolic]] [[Chemical reaction|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 [[enzyme inhibitor|inhibition]] is the primary method of regulating the amount of carbon entering the pathway.<ref name="Skikimate Pathway: Aromatic Amino Acids and Beyond">{{Cite doi|10.1038/npg.els.0001315}}</ref> Forms of this enzyme differ between organisms, but can be considered '''DAHP synthase''' based upon the reaction that is catalyzed by this enzyme.
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| In [[enzymology]], a DAHP synthase ({{EC number|2.5.1.54}}) is an [[enzyme]] that [[catalysis|catalyzes]] the [[chemical reaction]]
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| :phosphoenolpyruvate + D-erythrose 4-phosphate + H<sub>2</sub>O <math>\rightleftharpoons</math> 3-deoxy-D-arabino-hept-2-ulosonate 7-phosphate + phosphate
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| The three [[substrate (biochemistry)|substrates]] of this enzyme are [[phosphoenolpyruvate]], [[D-erythrose 4-phosphate]], and [[water|H<sub>2</sub>O]], whereas its two [[product (chemistry)|products]] are [[3-deoxy-D-arabino-hept-2-ulosonate 7-phosphate]] and [[phosphate]].
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| == Nomenclature == | |
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| This enzyme belongs to the family of [[transferase]]s, to be specific those transferring aryl or alkyl groups other than methyl groups. The systematic name of this enzyme class is '''phosphoenolpyruvate:D-erythrose-4-phosphate C-(1-carboxyvinyl)transferase (phosphate-hydrolysing, 2-carboxy-2-oxoethyl-forming)'''. Other names in common use include '''2-dehydro-3-deoxy-phosphoheptonate aldolase''', '''2-keto-3-deoxy-D-arabino-heptonic acid 7-phosphate synthetase''', '''3-deoxy-D-arabino-2-heptulosonic acid 7-phosphate synthetase''', '''3-deoxy-D-arabino-heptolosonate-7-phosphate synthetase''', '''3-deoxy-D-arabino-heptulosonate 7-phosphate synthetase''', '''7-phospho-2-keto-3-deoxy-D-arabino-heptonate D-erythrose-4-phosphate''', '''lyase (pyruvate-phosphorylating)''', '''7-phospho-2-dehydro-3-deoxy-D-arabino-heptonate''', '''D-erythrose-4-phosphate lyase (pyruvate-phosphorylating)''', '''D-erythrose-4-phosphate-lyase''', '''D-erythrose-4-phosphate-lyase (pyruvate-phosphorylating)''', '''DAH7-P synthase''', '''DAHP synthase''', '''DS-Co''', '''DS-Mn''', '''KDPH synthase''', '''KDPH synthetase''', '''deoxy-D-arabino-heptulosonate-7-phosphate synthetase''', '''phospho-2-dehydro-3-deoxyheptonate aldolase''', '''phospho-2-keto-3-deoxyheptanoate aldolase''', '''phospho-2-keto-3-deoxyheptonate aldolase''', '''phospho-2-keto-3-deoxyheptonic aldolase''', and '''phospho-2-oxo-3-deoxyheptonate aldolase'''.
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| ==Biological function==
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| The primary function of DAHP synthase is to catalyze the reaction of [[phosphoenolpyruvate]] and D-erythrose 4-phosphate to DAHP and [[phosphate]]. However, another biological function of the enzyme is to regulate the amount of carbon that enters the shikimate pathway. This is accomplished primarily through two different methods, feedback inhibition and transcriptional control.<ref name="Skikimate Pathway: Aromatic Amino Acids and Beyond" /> Feedback inhibition and transcriptional control are both mechanisms of regulating carbon in bacteria, but the only mechanism of regulation found in DAHP synthase found in plants is transcriptional control.<ref name="Skikimate Pathway: Aromatic Amino Acids and Beyond" />
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| In ''[[Escherichia coli]]'', a species of bacteria, DAHP synthase is found as three [[isoenzymes]], each of which sensitive to one of the amino acids produced in the shikimate pathway.<ref name="Schoner and Hermann Kinetics">{{Cite pmid|9387}}</ref> In a study of DAHP synthase sensitive to tyrosine in E. coli, it was determined that the enzyme is inhibited by tyrosine through noncompetitive inhibition with respect to [[phosphoenolpyruvate]], the first substrate of the reaction catalyzed by DAHP synthase, while the enzyme is inhibited by tyrosine through competitive inhibition with respect to D-erythrose 4-phosphate, the second substrate of the reaction catalyzed by DAHP synthase when the concentration of tyrosine is above 10 μM.<ref name="Schoner and Hermann Kinetics" /> It was also determined that the enzyme is inhibited by inorganic phosphate through noncompetitive inhibition with respect to both substrates and inhibited by DAHP through competitive inhibition with respect to [[phosphoenolpyruvate]] and noncompetitive inhibition with respect to D-erythrose 4-phosphate.<ref name="Schoner and Hermann Kinetics" /> Studies of product inhibition have shown that [[phosphoenolpyruvate]] is the first substrate to bind to the enzyme complex, inorganic [[phosphate]] is the first product to dissociate from the enzyme complex.<ref name="Schoner and Hermann Kinetics" /> Thus the amount of carbon entering the shikimate pathway can be controlled by inhibiting DAHP synthase from catalyzing the reaction that forms DAHP.
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| Carbon flow into the shikimate pathway in plants is regulated by transcriptional control.<ref name="Schoner and Hermann Kinetics" /> This method is also found in bacteria, but feedback inhibition is more prevalent.<ref name="Skikimate Pathway: Aromatic Amino Acids and Beyond" /> In plants, as the plants progressed through the growth cycle, the activity of DAHP synthase changed.<ref name="Skikimate Pathway: Aromatic Amino Acids and Beyond" />
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| ==Catalytic activity==
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| Metal ions are required in order for DAHP synthase to catalyze reactions.<ref name="Skikimate Pathway: Aromatic Amino Acids and Beyond" /> In DAHP synthase, it has been shown that binding site contains patterns of [[cysteine]] and [[histidine]] residues bound to metal ions in a Cys-X-X-His fashion.<ref name="Skikimate Pathway: Aromatic Amino Acids and Beyond" />
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| It has been shown that, in general, DAHP synthases require a bivalent metal ion [[Cofactor (biochemistry)|cofactor]] in order for the enzyme to function properly.<ref name="Metal Ion Cofactor">{{Cite pmid|1682314}}</ref> Metal ions that can function as cofactors include Mn<sup>2+</sup>, Fe<sup>2+</sup>, Co<sup>2+</sup>, Zn<sup>2+</sup>, Cu<sup>2+</sup>, and Ca<sup>2+</sup>.<ref name="Metal Ion Cofactor" /> Studies have suggested that one metal ion bonds to each monomer of DAHP synthase.<ref name="Metal Ion Cofactor" />
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| The reaction catalyzed by DAHP synthase is shown below.
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| [[Image:DAHP synthase reaction 2.png|thumb|center|500px|This is the reaction catalyzed by DAHP synthase.]]
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| ==Structure==
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| [[File:DAHP synthase quarternary structure.png|thumb|right|300px|This image shows the quaternary structure of DAHP synthase.]]
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| [[File:DAHP synthase cartoon quartenary structure.png|thumb|right|300px|This image shows the quaternary structure of DAHP synthase, with the secondary and tertiary structures illustrated in cartoon form.]]
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| The quaternary structure of DAHP synthase consists of two tightly bound [[Protein dimer|dimers]], which means that DAHP synthase is a [[tetramer]].<ref name="Crystal Structure">{{Cite doi|10.1016/S0969-2126(99)80109-9}}</ref>
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| To the right is an image of DAHP synthase that shows the quaternary structure of DAHP synthase. This image shows that DAHP synthase consists of two tightly bound dimers. Each of the monomer chains is colored differently.
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| Below the first image to the right is an image of DAHP synthase that also shows quaternary structure, however this image is in a cartoon view. This view also shows each of the four monomers colored differently. In addition, this view can also be used to show secondary and tertiary structures. As shown, two of the monomers have beta sheets that interact on one side of the enzyme, while the other two monomers have beta sheets that interact on the opposite side.
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| ==Structural studies==
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| As of late 2007, four [[tertiary structure|structures]] have been solved for this class of enzymes, with [[Protein Data Bank|PDB]] accession codes {{PDB link|1RZM}}, {{PDB link|1VR6}}, {{PDB link|1VS1}}, and {{PDB link|2B7O}}.
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| ==References==
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| {{reflist|1}}
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| ==Further reading==
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| * {{cite journal | author = Srinivasan PR and Sprinson DB | year = 1959 | title = 2-Keto-3-deoxy-D-arabo-heptonic acid 7-phosphate synthetase | journal = [[J. Biol. Chem.]] | volume = 234 | issue = 4 | pages = 716–722 | pmid=13654249}}
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| * {{cite journal | author = Jossek R, Bongaerts J, Sprenger GA | year = 2001 | title = Characterization of a new feedback-resistant 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase AroF of Escherichia coli | journal = [[FEMS Microbiol. Lett.]] | volume = 202 | pages = 145–8 | pmid = 11506923 | issue = 1 }}
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| * {{cite journal | author = Schneider TR, Hartmann M, Braus GH | date = Pt 9 | title = Crystallization and preliminary X-ray analysis of 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase (tyrosine inhibitable) from Saccharomyces cerevisiae | journal = [[Acta Crystallogr. D]] | volume = 55 | pages = 1586–8 | pmid = 10489454 | doi = 10.1107/S0907444999007830 | issue = Pt 9 }}
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| {{Collapse top|Pfam infoboxes for DAHP-synthase domains}}
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| {|
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| |{{Infobox protein family
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| | Symbol = DAHP_synth_2
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| | Name = Class-II DAHP synthetase family
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| | image =
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| | width =
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| | caption =
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| | Pfam = PF01474
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| | Pfam_clan = CL0036
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| | InterPro = IPR002480
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| | SMART =
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| | PROSITE =
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| | MEROPS =
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| | SCOP =
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| | TCDB =
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| | OPM family =
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| | OPM protein =
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| | CAZy =
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| | CDD =
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| }}
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| |}
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| {{Collapse bottom}}
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| {{DEFAULTSORT:3-Deoxy-7-Phosphoheptulonate Synthase}}
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| [[Category:EC 2.5.1]]
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| [[Category:Cadmium enzymes]]
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| [[Category:Enzymes of known structure]]
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ӏ'm a 32 years old, married and working at the high scɦool (Athletics and Physical Education).
In my spare time I learn Portugueѕe.
I have been tɦere and looκ forward to go there ѕоmetime in the future. I love to read, preferably on my kindle. I like to watch Grey's Anatomy and Supernatսral as well as documentaгies aЬout nature. I like Mountain bikіng.
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