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1mfv

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(New page: 200px<br /> <applet load="1mfv" size="450" color="white" frame="true" align="right" spinBox="true" caption="1mfv, resolution 2.00&Aring;" /> '''Probing the role of...)
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[[Image:1mfv.gif|left|200px]]<br />
 
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<applet load="1mfv" size="450" color="white" frame="true" align="right" spinBox="true"
 
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caption="1mfv, resolution 2.00&Aring;" />
 
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'''Probing the role of a mobile loop in human slaivary amylase: Structural studies on the loop-deleted enzyme'''<br />
 
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==Overview==
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==Probing the role of a mobile loop in human slaivary amylase: Structural studies on the loop-deleted enzyme==
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Mammalian amylases harbor a flexible, glycine-rich loop 304GHGAGGA(310), which becomes ordered upon oligosaccharide binding and moves in toward the, substrate. In order to probe the role of this loop in catalysis, a, deletion mutant lacking residues 306-310 (Delta306) was generated. Kinetic, studies showed that Delta306 exhibited: (1) a reduction (&gt;200-fold) in the, specific activity using starch as a substrate; (2) a reduction in k(cat), for maltopentaose and maltoheptaose as substrates; and (3) a twofold, increase in K(m) (maltopentaose as substrate) compared to the wild-type, (rHSAmy). More cleavage sites were observed for the mutant than for, rHSAmy, suggesting that the mutant exhibits additional productive binding, modes. Further insight into its role is obtained from the crystal, structures of the two enzymes soaked with acarbose, a transition-state, analog. Both enzymes modify acarbose upon binding through hydrolysis, condensation or transglycosylation reactions. Electron density, corresponding to six and seven fully occupied subsites in the active site, of rHSAmy and Delta306, respectively, were observed. Comparison of the, crystal structures showed that: (1) the hydrophobic cover provided by the, mobile loop for the subsites at the reducing end of the rHSAmy complex is, notably absent in the mutant; (2) minimal changes in the protein-ligand, interactions around subsites S1 and S1', where the cleavage would occur;, (3) a well-positioned water molecule in the mutant provides a hydrogen, bond interaction similar to that provided by the His305 in rHSAmy complex;, (4) the active site-bound oligosaccharides exhibit minimal conformational, differences between the two enzymes. Collectively, while the kinetic data, suggest that the mobile loop may be involved in assisting the catalysis, during the transition state, crystallographic data suggest that the loop, may play a role in the release of the product(s) from the active site.
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<StructureSection load='1mfv' size='340' side='right'caption='[[1mfv]], [[Resolution|resolution]] 2.00&Aring;' scene=''>
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== Structural highlights ==
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<table><tr><td colspan='2'>[[1mfv]] 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=1MFV OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1MFV 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=AGL:4,6-DIDEOXY-4-AMINO-ALPHA-D-GLUCOSE'>AGL</scene>, <scene name='pdbligand=BGC:BETA-D-GLUCOSE'>BGC</scene>, <scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=GLC:ALPHA-D-GLUCOSE'>GLC</scene>, <scene name='pdbligand=HMC:5-HYDROXYMETHYL-CHONDURITOL'>HMC</scene>, <scene name='pdbligand=PCA:PYROGLUTAMIC+ACID'>PCA</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=1mfv FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1mfv OCA], [https://pdbe.org/1mfv PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1mfv RCSB], [https://www.ebi.ac.uk/pdbsum/1mfv PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1mfv 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/mf/1mfv_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=1mfv 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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1MFV is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with GLC, CA and CL as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Alpha-amylase Alpha-amylase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.1 3.2.1.1] Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1MFV OCA].
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*[[Amylase 3D structures|Amylase 3D structures]]
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== References ==
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==Reference==
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<references/>
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Probing the role of a mobile loop in substrate binding and enzyme activity of human salivary amylase., Ramasubbu N, Ragunath C, Mishra PJ, J Mol Biol. 2003 Jan 31;325(5):1061-76. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=12527308 12527308]
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__TOC__
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[[Category: Alpha-amylase]]
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</StructureSection>
[[Category: Homo sapiens]]
[[Category: Homo sapiens]]
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[[Category: Single protein]]
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[[Category: Large Structures]]
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[[Category: Mishra, P.J.]]
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[[Category: Mishra PJ]]
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[[Category: Ragunath, C.]]
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[[Category: Ragunath C]]
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[[Category: Ramasubbu, N.]]
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[[Category: Ramasubbu N]]
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[[Category: CA]]
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[[Category: CL]]
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[[Category: GLC]]
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[[Category: acarbose]]
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[[Category: amylase]]
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[[Category: inhibitor]]
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[[Category: mutagenesis]]
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''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Mon Nov 12 18:10:53 2007''
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Current revision

Probing the role of a mobile loop in human slaivary amylase: Structural studies on the loop-deleted enzyme

PDB ID 1mfv

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