View source for 1btc


==THREE-DIMENSIONAL STRUCTURE OF SOYBEAN BETA-AMYLASE DETERMINED AT 3.0 ANGSTROMS RESOLUTION: PRELIMINARY CHAIN TRACING OF THE COMPLEX WITH ALPHA-CYCLODEXTRIN==
<StructureSection load='1btc' size='340' side='right'caption='[[1btc]], [[Resolution|resolution]] 2.00&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1btc]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Glycine_max Glycine max]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1BTC OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1BTC 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&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=BME:BETA-MERCAPTOETHANOL'>BME</scene>, <scene name='pdbligand=GLC:ALPHA-D-GLUCOSE'>GLC</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</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=1btc FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1btc OCA], [https://pdbe.org/1btc PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1btc RCSB], [https://www.ebi.ac.uk/pdbsum/1btc PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1btc ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/AMYB_SOYBN AMYB_SOYBN] 
== 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/bt/1btc_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview03.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=1btc ConSurf].
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== Publication Abstract from PubMed ==
New crystallographic findings are presented which offer a deeper understanding of the structure and functioning of beta-amylase, the first known exo-type starch-hydrolyzing enzyme. A refined three-dimensional structure of soybean beta-amylase, complexed with the inhibitor alpha-cyclodextrin, has been determined at 2.0-A resolution with a conventional R-value of 17.5%. The model contains 491 amino acid residues, 319 water molecules, 1 sulfate ion, and 1 alpha-cyclodextrin molecule. The protein consists of a core with an (alpha/beta)8 supersecondary structure, plus a smaller globular region formed by long loops (L3, L4, and L5) extending from beta-strands beta 3, beta 4, and beta 5. Between the two regions is a cleft that opens into a pocket whose floor contains the postulated catalytic center near the carboxyl group of Glu 186. The annular alpha-cyclodextrin binds in (and partly projects from) the cleft with its glucosyl O-2/O-3 face abutting the (alpha/beta)8 side and with its alpha-D(1 --&gt; 4) glucosidic linkage progression running clockwise as viewed from that side. The ligand does not bind deeply enough to interact with the carboxyl group of Glu 186. Rather, it occupies most of the cleft entrance, strongly suggesting that alpha-cyclodextrin inhibits catalysis by blocking substrate access to the more deeply located reaction center. Of the various alpha-cyclodextrin interactions with protein residues in loops L4, L5, L6, and L7, most notable is the shallow inclusion complex formed with Leu 383 (in L7, on the core side of the cleft) through contacts of its methyl groups with the C-3 atoms of four of the ligand's D-glucopyranosyl residues. All six residues of the bound alpha-cyclodextrin are of 4C1 conformation and are joined by alpha-1,4 linkages with similar torsional angles to form a nearly symmetrical torus as reported for crystalline inclusion complexes with alpha-cyclodextrin. We envision a significant role for the methyl groups of Leu 383 at the cleft entrance with respect to the productive binding of the outer chains of starch.

The 2.0-A resolution structure of soybean beta-amylase complexed with alpha-cyclodextrin.,Mikami B, Hehre EJ, Sato M, Katsube Y, Hirose M, Morita Y, Sacchettini JC Biochemistry. 1993 Jul 13;32(27):6836-45. PMID:8334116<ref>PMID:8334116</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 1btc" style="background-color:#fffaf0;"></div>

==See Also==
*[[Amylase 3D structures|Amylase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Glycine max]]
[[Category: Large Structures]]
[[Category: Hehre EJ]]
[[Category: Hirose M]]
[[Category: Katsube Y]]
[[Category: Mikami B]]
[[Category: Morita Y]]
[[Category: Sacchettini JC]]
[[Category: Sato M]]