1q4n

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{{Seed}}
 
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[[Image:1q4n.png|left|200px]]
 
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==Structural studies of Phe256Trp of human salivary alpha-amylase: implications for the role of a conserved water molecule and its associated chain in enzyme activity==
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The line below this paragraph, containing "STRUCTURE_1q4n", creates the "Structure Box" on the page.
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<StructureSection load='1q4n' size='340' side='right'caption='[[1q4n]], [[Resolution|resolution]] 2.07&Aring;' scene=''>
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You may change the PDB parameter (which sets the PDB file loaded into the applet)
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== Structural highlights ==
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or the SCENE parameter (which sets the initial scene displayed when the page is loaded),
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<table><tr><td colspan='2'>[[1q4n]] is a 1 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=1Q4N OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1Q4N FirstGlance]. <br>
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or leave the SCENE parameter empty for the default display.
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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]] 2.07&#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=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=PCA:PYROGLUTAMIC+ACID'>PCA</scene>, <scene name='pdbligand=TAM:TRIS(HYDROXYETHYL)AMINOMETHANE'>TAM</scene></td></tr>
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{{STRUCTURE_1q4n| PDB=1q4n | SCENE= }}
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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=1q4n FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1q4n OCA], [https://pdbe.org/1q4n PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1q4n RCSB], [https://www.ebi.ac.uk/pdbsum/1q4n PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1q4n ProSAT]</span></td></tr>
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</table>
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== Function ==
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[https://www.uniprot.org/uniprot/AMY1A_HUMAN AMY1A_HUMAN] Calcium-binding enzyme that initiates starch digestion in the oral cavity (PubMed:12527308). Catalyzes the hydrolysis of internal (1->4)-alpha-D-glucosidic bonds, yielding a mixture of maltose, isomaltose, small amounts of glucose as well as small linear and branched oligosaccharides called dextrins (PubMed:12527308).<ref>PMID:12527308</ref>
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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/q4/1q4n_consurf.spt"</scriptWhenChecked>
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<scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview03.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=1q4n ConSurf].
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<div style="clear:both"></div>
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<div style="background-color:#fffaf0;">
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== Publication Abstract from PubMed ==
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In the mechanism of hydrolysis of starch by alpha-amylases, a conserved water molecule bridging two catalytic residues has been implicated. In human salivary alpha-amylase (HSAmy), this water (W641), observed in many alpha-amylase structures, is part of a chain of water molecules. To test the hypothesis that W641 may be involved in the mechanism, Phe256 in the close vicinity was mutated to a Trp residue. X-ray structure of F256W complexed to 2-amino-2-(hydroxyethyl)-1,3-propanediol at 2.1A revealed that the water chain is disrupted. In the F256W structure exhibits a positional shift in His305, characteristic of alpha-amylase complex structures. Kinetic analysis, in comparison with HSAmy, revealed that the mutant exhibited a 70-fold decrease in the specific activity for starch and significantly reduced k(cat) (20-fold) and K(m) (4-fold) for maltoheptaoside. Collectively, these results suggest that W641 and the chain of water molecules may be critical for the alpha-amylase activity.
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===Structural studies of Phe256Trp of human salivary alpha-amylase: implications for the role of a conserved water molecule and its associated chain in enzyme activity===
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Structural studies of a Phe256Trp mutant of human salivary alpha-amylase: implications for the role of a conserved water molecule in enzyme activity.,Ramasubbu N, Sundar K, Ragunath C, Rafi MM Arch Biochem Biophys. 2004 Jan 1;421(1):115-24. PMID:14678792<ref>PMID:14678792</ref>
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From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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</div>
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<div class="pdbe-citations 1q4n" style="background-color:#fffaf0;"></div>
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==See Also==
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The line below this paragraph, {{ABSTRACT_PUBMED_14678792}}, adds the Publication Abstract to the page
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*[[Amylase 3D structures|Amylase 3D structures]]
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(as it appears on PubMed at http://www.pubmed.gov), where 14678792 is the PubMed ID number.
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== References ==
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<references/>
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{{ABSTRACT_PUBMED_14678792}}
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__TOC__
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</StructureSection>
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==About this Structure==
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1Q4N is a 1 chain structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1Q4N OCA].
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==Reference==
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<ref group="xtra">PMID:14678792</ref><references group="xtra"/>
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[[Category: Alpha-amylase]]
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[[Category: Homo sapiens]]
[[Category: Homo sapiens]]
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[[Category: Ramasubbu, N.]]
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[[Category: Large Structures]]
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[[Category: Amylase]]
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[[Category: Ramasubbu N]]
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[[Category: Inhibitor]]
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[[Category: Mutagenesis]]
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[[Category: Tri]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Feb 17 10:36:29 2009''
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Current revision

Structural studies of Phe256Trp of human salivary alpha-amylase: implications for the role of a conserved water molecule and its associated chain in enzyme activity

PDB ID 1q4n

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