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==X-ray crystal structure of the E249Q mutant of alpha-amylase I from Eisenia fetida==
<StructureSection load='6m4l' size='340' side='right'caption='[[6m4l]], [[Resolution|resolution]] 1.60&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6M4L OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6M4L 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]] 1.6&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=ACT:ACETATE+ION'>ACT</scene>, <scene name='pdbligand=CA:CALCIUM+ION'>CA</scene>, <scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=EDO:1,2-ETHANEDIOL'>EDO</scene>, <scene name='pdbligand=PG4:TETRAETHYLENE+GLYCOL'>PG4</scene>, <scene name='pdbligand=PGE:TRIETHYLENE+GLYCOL'>PGE</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene>, <scene name='pdbligand=TRS:2-AMINO-2-HYDROXYMETHYL-PROPANE-1,3-DIOL'>TRS</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=6m4l FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6m4l OCA], [https://pdbe.org/6m4l PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6m4l RCSB], [https://www.ebi.ac.uk/pdbsum/6m4l PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6m4l ProSAT]</span></td></tr>
</table>
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== Publication Abstract from PubMed ==
The earthworm Eisenia fetida possesses several cold-active enzymes, including alpha-amylase, beta-glucanase and beta-mannanase. E. fetida possesses two isoforms of alpha-amylase (Ef-Amy I and II) to digest raw starch. Ef-Amy I retains its catalytic activity at temperatures below 10 degrees C. To identify the molecular properties of Ef-Amy I, X-ray crystal structures were determined of the wild type and of the inactive E249Q mutant. Ef-Amy I has structural similarities to mammalian alpha-amylases, including the porcine pancreatic and human pancreatic alpha-amylases. Structural comparisons of the overall structures as well as of the Ca(2+)-binding sites of Ef-Amy I and the mammalian alpha-amylases indicate that Ef-Amy I has increased structural flexibility and more solvent-exposed acidic residues. These structural features of Ef-Amy I may contribute to its observed catalytic activity at low temperatures, as many cold-adapted enzymes have similar structural properties. The structure of the substrate complex of the inactive mutant of Ef-Amy I shows that a maltohexaose molecule is bound in the active site and a maltotetraose molecule is bound in the cleft between the N- and C-terminal domains. The recognition of substrate molecules by Ef-Amy I exhibits some differences from that observed in structures of human pancreatic alpha-amylase. This result provides insights into the structural modulation of the recognition of substrates and inhibitors.

X-ray crystallographic structural studies of alpha-amylase I from Eisenia fetida.,Hirano Y, Tsukamoto K, Ariki S, Naka Y, Ueda M, Tamada T Acta Crystallogr D Struct Biol. 2020 Sep 1;76(Pt 9):834-844. doi:, 10.1107/S2059798320010165. Epub 2020 Aug 25. PMID:32876059<ref>PMID:32876059</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 6m4l" style="background-color:#fffaf0;"></div>

==See Also==
*[[Amylase 3D structures|Amylase 3D structures]]
== References ==
<references/>
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</StructureSection>
[[Category: Large Structures]]
[[Category: Ariki S]]
[[Category: Hirano Y]]
[[Category: Naka Y]]
[[Category: Tamada T]]
[[Category: Tsukamoto K]]
[[Category: Ueda M]]