View source for 2e5b


==Crystal structure of Human NMPRTase as free-form==
<StructureSection load='2e5b' size='340' side='right'caption='[[2e5b]], [[Resolution|resolution]] 2.00&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[2e5b]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2E5B OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2E5B FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2&#8491;</td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=2e5b FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2e5b OCA], [https://pdbe.org/2e5b PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2e5b RCSB], [https://www.ebi.ac.uk/pdbsum/2e5b PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2e5b ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/NAMPT_HUMAN NAMPT_HUMAN] Catalyzes the condensation of nicotinamide with 5-phosphoribosyl-1-pyrophosphate to yield nicotinamide mononucleotide, an intermediate in the biosynthesis of NAD. It is the rate limiting component in the mammalian NAD biosynthesis pathway (By similarity).
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/e5/2e5b_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=2e5b ConSurf].
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== Publication Abstract from PubMed ==
Nicotinamide (NM) phosphoribosyltransferase (NMPRTase) catalyzes the reaction of NM and 5'-phosphoribosyl-1'-pyrophosphate (PRPP) to form NM mononucleotide (NMN) and pyrophosphate (PPi) in the pathway of NAD-biosynthesis. Monitoring the (1)H and (31)P NMR spectra of the reaction mixture, we found that this reaction is reversible as dictated by the equilibrium constant K = [NMN][PPi]/([NM][PRPP]) = 0.14, which agreed well with the ratio of second-order rate constants for forward and backward reactions, K = 0.16. The crystal structures of this enzyme in the free form and bound to NM and PRPP at the resolution of 2.0-2.2 A were essentially identical to that of the complex with NMN, except for some variations that could facilitate the substitution reaction by fixing the nucleophile and the leaving group for the requisite inversion of configuration at the C1' carbon of the ribose ring. In the active site near the C1' atom of the bound PRPP or NMN, there was neither negatively charged group nor waterproof environment necessary to support the feasibility of a ribo-oxocarbocation intermediate inherent in the S(N)1 mechanism. The structures and catalytic mechanism thus revealed are also discussed in connection with the multiple biological functions of NMPRTase.

Structure and reaction mechanism of human nicotinamide phosphoribosyltransferase.,Takahashi R, Nakamura S, Nakazawa T, Minoura K, Yoshida T, Nishi Y, Kobayashi Y, Ohkubo T J Biochem. 2010 Jan;147(1):95-107. Epub 2009 Oct 9. PMID:19819904<ref>PMID:19819904</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 2e5b" style="background-color:#fffaf0;"></div>

==See Also==
*[[Phosphoribosyltransferase 3D structures|Phosphoribosyltransferase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Kobayashi Y]]
[[Category: Nakamura S]]
[[Category: Ohkubo T]]
[[Category: Takahashi R]]