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1gah

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[[Image:1gah.gif|left|200px]]<br /><applet load="1gah" size="450" color="white" frame="true" align="right" spinBox="true"
 
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caption="1gah, resolution 2.0&Aring;" />
 
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'''GLUCOAMYLASE-471 COMPLEXED WITH ACARBOSE'''<br />
 
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==Overview==
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==GLUCOAMYLASE-471 COMPLEXED WITH ACARBOSE==
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Crystal structures at pH 4 of complexes of glucoamylase from Aspergillus, awamori var. X100 with the pseudotetrasaccharides D-gluco-dihydroacarbose, and acarbose have been refined to R-factors of 0.147 and 0.131 against, data to 1.7- and 2.0-A resolution, respectively. The two inhibitors bind, in nearly identical manners, each exhibiting a dual binding mode with, respect to the location of the last sugar residues. The reduced affinity, of D-gluco-dihydroacarbose (K1 = 10(-8) M) relative to acarbose (K1 =, 10(-12) M) may stem in part from the weakening of hydrogen bonds of the, catalytic water (Wat 500) to the enzyme. Steric contacts between the, nonreducing end of D-gluco-dihydroacarbose and the catalytic water perturb, Wat 500 from its site of optimal hydrogen bonding to the active site., Interactions within the active site displace the 6-hydroxymethyl group of, the nonreducing end of both acarbose and D-gluco-dihydroacarbose toward a, more axial position. In the case of D-gluco-dihydroacarbose the shift in, the position of the 6-hydroxymethyl group occurs with a 12 degrees change, in two dihedral angles of the glucopyranose ring toward a half-chair, conformation. The observed conformational distortion of the first residue, of D-gluco-dihydroacarbose is consistent with the generation of a, glucopyranosyl cation in the transition state. Comparable distortions of, stereochemistry in model compounds require approximately 2 kcal/mol, not, more than 25% of the energy necessary to form the half-chair conformation, in glucose. The magnitude of stereochemical distortion observed in the, active site of glucoamylase suggests that favorable electrostatic, interactions between the putative glucopyranosyl cation intermediate and, the active site must be more important in stabilizing the transition state, than mechanical distortion of the substrate.
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<StructureSection load='1gah' size='340' side='right'caption='[[1gah]], [[Resolution|resolution]] 2.00&Aring;' scene=''>
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== Structural highlights ==
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<table><tr><td colspan='2'>[[1gah]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Aspergillus_awamori Aspergillus awamori]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1GAH OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1GAH FirstGlance]. <br>
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</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>
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<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=AC1:6-METHYL-5-(4,5,6-TRIHYDROXY-3-HYDROXYMETHYL-CYCLOHEX-2-ENYLAMINO)-TETRAHYDRO-PYRAN-2,3,4-TRIOL'>AC1</scene>, <scene name='pdbligand=BMA:BETA-D-MANNOSE'>BMA</scene>, <scene name='pdbligand=GLC:ALPHA-D-GLUCOSE'>GLC</scene>, <scene name='pdbligand=MAN:ALPHA-D-MANNOSE'>MAN</scene>, <scene name='pdbligand=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</scene>, <scene name='pdbligand=PRD_900007:alpha-acarbose'>PRD_900007</scene></td></tr>
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<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1gah FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1gah OCA], [https://pdbe.org/1gah PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1gah RCSB], [https://www.ebi.ac.uk/pdbsum/1gah PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1gah ProSAT]</span></td></tr>
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</table>
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== Function ==
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[https://www.uniprot.org/uniprot/AMYG_ASPAW AMYG_ASPAW]
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== Evolutionary Conservation ==
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[[Image:Consurf_key_small.gif|200px|right]]
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Check<jmol>
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<jmolCheckbox>
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<scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/ga/1gah_consurf.spt"</scriptWhenChecked>
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<scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
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<text>to colour the structure by Evolutionary Conservation</text>
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</jmolCheckbox>
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</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=1gah ConSurf].
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<div style="clear:both"></div>
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==About this Structure==
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==See Also==
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1GAH is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Aspergillus_awamori Aspergillus awamori] with MAN, ACR, SER and GLY as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Glucan_1,4-alpha-glucosidase Glucan 1,4-alpha-glucosidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.3 3.2.1.3] Known structural/functional Sites: <scene name='pdbsite=SB1:Binding Subsite For The First Residue Of Acarbose'>SB1</scene>, <scene name='pdbsite=SB2:Binding Subsite For The Second Residue Of Acarbose'>SB2</scene> and <scene name='pdbsite=SB3:Binding Subsite For The Third Residue Of Acarbose'>SB3</scene>. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1GAH OCA].
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*[[Alpha-glucosidase 3D structures|Alpha-glucosidase 3D structures]]
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*[[Amylase 3D structures|Amylase 3D structures]]
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==Reference==
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__TOC__
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Crystallographic complexes of glucoamylase with maltooligosaccharide analogs: relationship of stereochemical distortions at the nonreducing end to the catalytic mechanism., Aleshin AE, Stoffer B, Firsov LM, Svensson B, Honzatko RB, Biochemistry. 1996 Jun 25;35(25):8319-28. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=8679589 8679589]
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</StructureSection>
[[Category: Aspergillus awamori]]
[[Category: Aspergillus awamori]]
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[[Category: Glucan 1,4-alpha-glucosidase]]
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[[Category: Large Structures]]
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[[Category: Single protein]]
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[[Category: Aleshin AE]]
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[[Category: Aleshin, A.E.]]
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[[Category: Firsov LM]]
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[[Category: Firsov, L.M.]]
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[[Category: Honzatko RB]]
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[[Category: Honzatko, R.B.]]
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[[Category: Stoffer B]]
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[[Category: Stoffer, B.]]
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[[Category: Svensson B]]
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[[Category: Svensson, B.]]
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[[Category: ACR]]
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[[Category: GLY]]
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[[Category: MAN]]
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[[Category: SER]]
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[[Category: glycoprotein]]
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[[Category: glycosidase]]
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[[Category: hydrolase]]
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[[Category: polysaccharide degradation]]
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''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Tue Dec 18 15:18:50 2007''
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Current revision

GLUCOAMYLASE-471 COMPLEXED WITH ACARBOSE

PDB ID 1gah

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