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| | <StructureSection load='1m01' size='340' side='right'caption='[[1m01]], [[Resolution|resolution]] 2.10Å' scene=''> | | <StructureSection load='1m01' size='340' side='right'caption='[[1m01]], [[Resolution|resolution]] 2.10Å' scene=''> |
| | == Structural highlights == | | == Structural highlights == |
| - | <table><tr><td colspan='2'>[[1m01]] is a 1 chain structure with sequence from [http://en.wikipedia.org/wiki/Atcc_25483 Atcc 25483]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1M01 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1M01 FirstGlance]. <br> | + | <table><tr><td colspan='2'>[[1m01]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Atcc_25483 Atcc 25483]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1M01 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1M01 FirstGlance]. <br> |
| - | </td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=GOL:GLYCEROL'>GOL</scene>, <scene name='pdbligand=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene></td></tr> | + | </td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=GOL:GLYCEROL'>GOL</scene>, <scene name='pdbligand=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene></td></tr> |
| - | <tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[1m03|1m03]], [[1m04|1m04]], [[1hp5|1hp5]], [[1jak|1jak]]</td></tr> | + | <tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat"><div style='overflow: auto; max-height: 3em;'>[[1m03|1m03]], [[1m04|1m04]], [[1hp5|1hp5]], [[1jak|1jak]]</div></td></tr> |
| - | <tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/Beta-N-acetylhexosaminidase Beta-N-acetylhexosaminidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.52 3.2.1.52] </span></td></tr> | + | <tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[https://en.wikipedia.org/wiki/Beta-N-acetylhexosaminidase Beta-N-acetylhexosaminidase], with EC number [https://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.52 3.2.1.52] </span></td></tr> |
| - | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1m01 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1m01 OCA], [http://pdbe.org/1m01 PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1m01 RCSB], [http://www.ebi.ac.uk/pdbsum/1m01 PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=1m01 ProSAT]</span></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=1m01 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1m01 OCA], [https://pdbe.org/1m01 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1m01 RCSB], [https://www.ebi.ac.uk/pdbsum/1m01 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1m01 ProSAT]</span></td></tr> |
| | </table> | | </table> |
| | == Evolutionary Conservation == | | == Evolutionary Conservation == |
| Structural highlights
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
SpHex, a retaining family 20 glycosidase from Streptomyces plicatus, catalyzes the hydrolysis of N-acetyl-beta-hexosaminides. Accumulating evidence suggests that the hydrolytic mechanism involves substrate-assisted catalysis wherein the 2-acetamido substituent acts as a nucleophile to form an oxazolinium ion intermediate. The role of a conserved aspartate residue (D313) in the active site of SpHex was investigated through kinetic and structural analyses of two variant enzymes, D313A and D313N. Three-dimensional structures of the wild-type and variant enzymes in product complexes with N-acetyl-d-glucosamine revealed substantial differences. In the D313A variant the 2-acetamido group was found in two conformations of which only one is able to aid in catalysis through anchimeric assistance. The mutation D313N results in a steric clash in the active site between Asn-313 and the 2-acetamido group preventing the 2-acetamido group from providing anchimeric assistance, consistent with the large reduction in catalytic efficiency and the insensitivity of this variant to chemical rescue. By comparison, the D313A mutation results in a shift in a shift in the pH optimum and a modest decrease in activity that can be rescued by using azide as an exogenous nucleophile. These structural and kinetic data provide evidence that Asp-313 stabilizes the transition states flanking the oxazoline intermediate and also assists to correctly orient the 2-acetamido group for catalysis. Based on analogous conserved residues in the family 18 chitinases and family 56 hyaluronidases, the roles played by the Asp-313 residue is likely general for all hexosaminidases using a mechanism involving substrate-assisted catalysis.
Aspartate 313 in the Streptomyces plicatus hexosaminidase plays a critical role in substrate-assisted catalysis by orienting the 2-acetamido group and stabilizing the transition state.,Williams SJ, Mark BL, Vocadlo DJ, James MN, Withers SG J Biol Chem. 2002 Oct 18;277(42):40055-65. Epub 2002 Aug 8. PMID:12171933[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Williams SJ, Mark BL, Vocadlo DJ, James MN, Withers SG. Aspartate 313 in the Streptomyces plicatus hexosaminidase plays a critical role in substrate-assisted catalysis by orienting the 2-acetamido group and stabilizing the transition state. J Biol Chem. 2002 Oct 18;277(42):40055-65. Epub 2002 Aug 8. PMID:12171933 doi:http://dx.doi.org/10.1074/jbc.M206481200
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