1xym

<StructureSection load='1xym' size='340' side='right' caption='[[1xym]], [[Resolution|resolution]] 1.80&Aring;' scene=''>

<table><tr><td colspan='2'>[[1xym]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/"actinomyces_olivochromogenus"_(sic)_waksman_1923 "actinomyces olivochromogenus" (sic) waksman 1923]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1XYM OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1XYM FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=GLO:D-GLUCOSE+IN+LINEAR+FORM'>GLO</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=OH:HYDROXIDE+ION'>OH</scene></td></tr>

<tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/Xylose_isomerase Xylose isomerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.3.1.5 5.3.1.5] </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=1xym FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1xym OCA], [http://pdbe.org/1xym PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1xym RCSB], [http://www.ebi.ac.uk/pdbsum/1xym PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=1xym ProSAT]</span></td></tr>

[[http://www.uniprot.org/uniprot/XYLA_STROL XYLA_STROL]] Involved in D-xylose catabolism.

<scriptWhenChecked>select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/xy/1xym_consurf.spt"</scriptWhenChecked>

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== Publication Abstract from PubMed ==

The distinct roles of the two magnesium ions essential to the activity of D-xylose isomerase from Streptomyces olivochromogenes were examined. The enzyme-magnesium complex was isolated, and the stoichiometry of cation binding determined by neutron activation analysis to be 2 mol of magnesium per mole of enzyme. A plot of Mg2+ added versus Mg2+ bound to enzyme is consistent with apparent KD values of &lt; or = 0.5-1.0 mM for one Mg2+ and &lt; or = 2-5 mM for the second. A site-directed mutant of D-xylose isomerase was designed to remove the tighter, tetracoordinated magnesium binding site (site 1, Mg-1); Glu180 was replaced with Lys180. The stoichiometry of metal binding to this mutant, E180K, is 1 mol of magnesium per mole of enzyme. Ring-opening assays with 1-thioglucose (H2S released upon ring opening) show E180K catalyzes the opening of the sugar ring at 20% the rate of the wild-type, but E180K does not catalyze isomerization of glucose to fructose. Thus, the magnesium bound to Glu180 is essential for isomerization but not essential for ring opening. The X-ray crystallographic structures of E180K in the absence of magnesium and in the presence and absence of 250 mM glucose were obtained to 1.8-A resolution and refined to R factors of 17.7% and 19.7%, respectively. The wild-type and both E180K structures show no significant structural differences, except the epsilon-amino group of Lys180, which occupies the position usually occupied by the Mg-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of the divalent metal ion in sugar binding, ring opening, and isomerization by D-xylose isomerase: replacement of a catalytic metal by an amino acid.,Allen KN, Lavie A, Glasfeld A, Tanada TN, Gerrity DP, Carlson SC, Farber GK, Petsko GA, Ringe D Biochemistry. 1994 Feb 15;33(6):1488-94. PMID:7906142<ref>PMID:7906142</ref>

 

[[Category: Xylose isomerase]]

[[Category: Allen, K N]]

[[Category: Lavie, A]]

[[Category: Petsko, G A]]

[[Category: Ringe, D]]