1xym: Difference between revisions
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[[Image:1xym.gif|left|200px]] | [[Image:1xym.gif|left|200px]] | ||
'''THE 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''' | {{Structure | ||
|PDB= 1xym |SIZE=350|CAPTION= <scene name='initialview01'>1xym</scene>, resolution 1.8Å | |||
|SITE= | |||
|LIGAND= <scene name='pdbligand=GLO:D-GLUCOSE+IN+LINEAR+FORM'>GLO</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene> and <scene name='pdbligand=OH:HYDROXIDE ION'>OH</scene> | |||
|ACTIVITY= [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] | |||
|GENE= | |||
}} | |||
'''THE 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''' | |||
==Overview== | ==Overview== | ||
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==About this Structure== | ==About this Structure== | ||
1XYM is a [ | 1XYM is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Streptomyces_olivochromogenes Streptomyces olivochromogenes]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1XYM OCA]. | ||
==Reference== | ==Reference== | ||
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:[http:// | 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:[http://www.ncbi.nlm.nih.gov/pubmed/7906142 7906142] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Streptomyces olivochromogenes]] | [[Category: Streptomyces olivochromogenes]] | ||
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[[Category: isomerase(intramolecular oxidoreductase)]] | [[Category: isomerase(intramolecular oxidoreductase)]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Mar 20 15:16:12 2008'' | ||
Revision as of 16:16, 20 March 2008
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| , resolution 1.8Å | |||||||
|---|---|---|---|---|---|---|---|
| Ligands: | , and | ||||||
| Activity: | Xylose isomerase, with EC number 5.3.1.5 | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
THE 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
OverviewOverview
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 < or = 0.5-1.0 mM for one Mg2+ and < 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)
About this StructureAbout this Structure
1XYM is a Single protein structure of sequence from Streptomyces olivochromogenes. Full crystallographic information is available from OCA.
ReferenceReference
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
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