View source for 1noi


==COMPLEX OF GLYCOGEN PHOSPHORYLASE WITH A TRANSITION STATE ANALOGUE NOJIRIMYCIN TETRAZOLE AND PHOSPHATE IN THE T AND R STATES==
<StructureSection load='1noi' size='340' side='right'caption='[[1noi]], [[Resolution|resolution]] 2.50&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1noi]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Oryctolagus_cuniculus Oryctolagus cuniculus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1NOI OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1NOI 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]] 2.5&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=NTZ:NOJIRIMYCINE+TETRAZOLE'>NTZ</scene>, <scene name='pdbligand=PLP:PYRIDOXAL-5-PHOSPHATE'>PLP</scene>, <scene name='pdbligand=PO4:PHOSPHATE+ION'>PO4</scene></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=1noi FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1noi OCA], [https://pdbe.org/1noi PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1noi RCSB], [https://www.ebi.ac.uk/pdbsum/1noi PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1noi ProSAT]</span></td></tr>
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== Function ==
[https://www.uniprot.org/uniprot/PYGM_RABIT PYGM_RABIT] Phosphorylase is an important allosteric enzyme in carbohydrate metabolism. Enzymes from different sources differ in their regulatory mechanisms and in their natural substrates. However, all known phosphorylases share catalytic and structural properties.
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
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    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/no/1noi_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=1noi ConSurf].
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== Publication Abstract from PubMed ==
Catalysis by glycogen phosphorylase involves a mechanism in which binding of one substrate tightens the binding of the other substrate to produce a productive ternary enzyme-substrate complex. In this work the molecular basis for this synergism is probed in crystallographic studies on ternary complexes in which the glucosyl component is substituted by the putative transition state analogue nojirimycin tetrazole, a compound which has been established previously as a transition state analogue inhibitor for a number of glycosidases. Kinetic studies with glycogen phosphorylase showed that nojirimycin tetrazole is a competitive inhibitor with respect to glucose 1-phosphate and uncompetitive with respect to phosphate. Ki values for the phosphorylase-AMP-glycogen complex and the phosphorylase-AMP-glycogen-phosphate complexes are 700 microM and 53 microM, respectively, indicating that by itself norjirimycin tetrazole has poor affinity for glycogen phosphorylase but that phosphate substantially improves the binding of norjirimycin tetrazole. X-ray crystallographic binding studies to 2.4 A resolution with T state phosphorylase b crystals showed that nojirimycin tetrazole binds at the catalytic site and promotes the binding of phosphate through direct interactions. Phosphate binding is accompanied by conformational changes that bring a crucial arginine (Arg569) into the catalytic site. The positions of the phosphate oxygens were definitively established in X-ray crystallographic binding experiments at 100 K to 1.7 A resolution using synchrotron radiation. X-ray crystallographic binding studies at 2.5 A resolution with R state glycogen phosphorylase crystals showed that the protein atoms and water molecules in contact with the nojirimycin tetrazole and the phosphate are similar to those in the T state. In both T and R states the phosphate ion is within hydrogen-bonding distance of the cofactor pyridoxal 5'-phosphate group and in ionic contact with the N-1 atom of the tetrazole ring. The results are consistent with previous time-resolved structural studies on complexes with heptenitol and phosphate. The structural and kinetic results suggest that nojirimycin tetrazole in combination with phosphate exhibits properties consistent with a transition state analogue and demonstrate how one promotes the binding of the other.

Ternary complex crystal structures of glycogen phosphorylase with the transition state analogue nojirimycin tetrazole and phosphate in the T and R states.,Mitchell EP, Withers SG, Ermert P, Vasella AT, Garman EF, Oikonomakos NG, Johnson LN Biochemistry. 1996 Jun 11;35(23):7341-55. PMID:8652510<ref>PMID:8652510</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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==See Also==
*[[Glycogen phosphorylase 3D structures|Glycogen phosphorylase 3D structures]]
== References ==
<references/>
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</StructureSection>
[[Category: Large Structures]]
[[Category: Oryctolagus cuniculus]]
[[Category: Johnson LN]]
[[Category: Mitchell EP]]