View source for 5wqs


==Crystal structure of Apo Beta-Amylase from Sweet potato==
<StructureSection load='5wqs' size='340' side='right'caption='[[5wqs]], [[Resolution|resolution]] 1.90&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[5wqs]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Ipomoea_batatas Ipomoea batatas]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5WQS OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=5WQS 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]] 1.9&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=IPA:ISOPROPYL+ALCOHOL'>IPA</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=5wqs FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5wqs OCA], [https://pdbe.org/5wqs PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=5wqs RCSB], [https://www.ebi.ac.uk/pdbsum/5wqs PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=5wqs ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/AMYB_IPOBA AMYB_IPOBA] 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
The conversion of starch to maltose is catalysed in plants by beta-amylase. The enzymatic mechanism has been well-characterized for the soybean and barley enzymes, which utilise a glutamic acid-glutamate pair. In the present study, we present a surprise observation of maltotetraose at the active site, the presence of which elucidates the clear role of Thr344 as a conformational "switch" between substrate binding and product release during hydrolysis. This observation is confirmed by the selection of maltotetraose by the crystallized enzyme although that carbohydrate was present in only trace amounts. The conformation of the residues in the substrate-binding site changed upon substrate binding, leading to the movement of threonine, glutamic acid, and the loop conformation, elucidating a missing link in the existing mechanism. By aligning our substrate-free and maltotetraose-bound structures with other existing structures, the sequence of events from substrate binding to hydrolysis can be visualized. Apart from this, the evolutionary relationship among beta-amylases of bacterial and amyloplastic origin could be established. The presence of a sugar-binding domain in the bacterial enzyme and its absence in the plant counterpart could be attributed to a carbohydrate-rich environment. Interestingly, cladogram analysis indicates the presence of N-terminal additions in some plant beta-amylases. Based on sequence similarity, we postulate that the role of such additions is important for the regulation of enzymatic activity, particularly under stress conditions.

Structural insights on starch hydrolysis by plant beta-amylase and its evolutionary relationship with bacterial enzymes.,Vajravijayan S, Pletnev S, Mani N, Pletneva N, Nandhagopal N, Gunasekaran K Int J Biol Macromol. 2018 Jul 1;113:329-337. doi: 10.1016/j.ijbiomac.2018.02.138., Epub 2018 Feb 23. PMID:29481953<ref>PMID:29481953</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 5wqs" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Ipomoea batatas]]
[[Category: Large Structures]]
[[Category: Gunasekaran K]]
[[Category: Nandhagopal N]]
[[Category: Sergei P]]
[[Category: Vajravijayan S]]