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[[Image:1mas.gif|left|200px]]<br />
<applet load="1mas" size="450" color="white" frame="true" align="right" spinBox="true"
caption="1mas, resolution 2.5&Aring;" />
'''PURINE NUCLEOSIDE HYDROLASE'''<br />


==Overview==
==PURINE NUCLEOSIDE HYDROLASE==
Protozoan parasites rely on the host for purines since they lack a de novo, synthetic pathway. Crithidia fasciculata salvages exogenous inosine, primarily through hydrolysis of the N-ribosidic bond using several, nucleoside hydrolases. The most abundant nucleoside hydrolase is, relatively nonspecific but prefers inosine and uridine as substrates. Here, we report the three-dimensional structure of the inosine-uridine, nucleoside hydrolase (IU-NH) from C. fasciculata determined by X-ray, crystallography at a nominal resolution of 2.5 A. The enzyme has an open, (alpha, beta) structure which differs from the classical dinucleotide, binding fold. IU-nucleoside hydrolase is composed of a mixed, eight-stranded beta sheet surrounded by six alpha helices and a small, C-terminal lobe composed of four alpha helices. Two short antiparallel, beta strands are involved in intermolecular contacts. The catalytic pocket, is located at the C-terminal end of beta strands beta 1 and beta 4. Four, aspartate residues are located at the bottom of the cavity in a geometry, which suggests interaction with the ribose moiety of the nucleoside. These, groups could provide the catalytically important interactions to the, ribosyl hydroxyls and the stabilizing anion for the oxycarbonium-like, transition state. Histidine 241, located on the side of the active site, cavity, is the proposed proton donor which facilitates purine base, departure [Gopaul, D. N., Meyer, S. L., Degano, M., Sacchettini, J. C., &amp;, Schramm, V. L. (1996) Biochemistry 35, 5963-5970]. The substrate binding, site is unlike that from purine nucleoside phosphorylase, phosphoribosyltransferases, or uracil DNA glycosylase and thus represents, a novel architecture for general acid-base catalysis. This detailed, knowledge of the architecture of the active site, together with the, previous transition state analysis [Horenstein, B. A., Parkin, D. W., Estupinan, B., &amp; Schramm, V. L. (1991) Biochemistry 30, 10788-10795], allows analysis of the interactions leading to catalysis and an, explanation for the tight-binding inhibitors of the enzyme [Schramm, V., L., Horenstein, B. A., &amp; Kline, P. C. (1994) J. Biol. Chem. 269, 18259-18262].
<StructureSection load='1mas' size='340' side='right'caption='[[1mas]], [[Resolution|resolution]] 2.50&Aring;' scene=''>
 
== Structural highlights ==
==About this Structure==
<table><tr><td colspan='2'>[[1mas]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Crithidia_fasciculata Crithidia fasciculata]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1MAS OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1MAS FirstGlance]. <br>
1MAS is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Crithidia_fasciculata Crithidia fasciculata] with K as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Purine_nucleosidase Purine nucleosidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.2.1 3.2.2.1] Structure known Active Site: ACT. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1MAS OCA].
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.5&#8491;</td></tr>
 
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=K:POTASSIUM+ION'>K</scene></td></tr>
==Reference==
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1mas FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1mas OCA], [https://pdbe.org/1mas PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1mas RCSB], [https://www.ebi.ac.uk/pdbsum/1mas PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1mas ProSAT]</span></td></tr>
Three-dimensional structure of the inosine-uridine nucleoside N-ribohydrolase from Crithidia fasciculata., Degano M, Gopaul DN, Scapin G, Schramm VL, Sacchettini JC, Biochemistry. 1996 May 14;35(19):5971-81. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=8634238 8634238]
</table>
== Function ==
[https://www.uniprot.org/uniprot/IUNH_CRIFA IUNH_CRIFA] Catalyzes the hydrolysis of all of the commonly occurring purine and pyrimidine nucleosides into ribose and the associated base, but has a preference for inosine and uridine as substrates.
== 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/ma/1mas_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=1mas ConSurf].
<div style="clear:both"></div>
__TOC__
</StructureSection>
[[Category: Crithidia fasciculata]]
[[Category: Crithidia fasciculata]]
[[Category: Purine nucleosidase]]
[[Category: Large Structures]]
[[Category: Single protein]]
[[Category: Degano M]]
[[Category: Degano, M.]]
[[Category: Gopaul DN]]
[[Category: Gopaul, D.N.]]
[[Category: Sacchettini JC]]
[[Category: Sacchettini, J.C.]]
[[Category: Scapin G]]
[[Category: Scapin, G.]]
[[Category: Schramm VL]]
[[Category: Schramm, V.L.]]
[[Category: K]]
[[Category: hydrolase]]
[[Category: iu-nh]]
[[Category: purine nucleosidase]]
[[Category: purine nucleoside hydrolase]]
 
''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Mon Nov  5 16:42:56 2007''

Latest revision as of 10:42, 14 February 2024

PURINE NUCLEOSIDE HYDROLASEPURINE NUCLEOSIDE HYDROLASE

Structural highlights

1mas is a 2 chain structure with sequence from Crithidia fasciculata. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:X-ray diffraction, Resolution 2.5Å
Ligands:
Resources:FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

IUNH_CRIFA Catalyzes the hydrolysis of all of the commonly occurring purine and pyrimidine nucleosides into ribose and the associated base, but has a preference for inosine and uridine as substrates.

Evolutionary Conservation

Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.

1mas, resolution 2.50Å

Drag the structure with the mouse to rotate

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