1s5m
From Proteopedia
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| - | [[Image:1s5m.gif|left|200px]] | + | [[Image:1s5m.gif|left|200px]] |
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| - | '''Xylose Isomerase in Substrate and Inhibitor Michaelis States: Atomic Resolution Studies of a Metal-Mediated Hydride Shift''' | + | {{Structure |
| + | |PDB= 1s5m |SIZE=350|CAPTION= <scene name='initialview01'>1s5m</scene>, resolution 0.98Å | ||
| + | |SITE= | ||
| + | |LIGAND= <scene name='pdbligand=GLC:GLUCOSE'>GLC</scene>, <scene name='pdbligand=MN:MANGANESE+(II)+ION'>MN</scene> and <scene name='pdbligand=NA:SODIUM ION'>NA</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= XYLA ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=1963 Streptomyces olivochromogenes]) | ||
| + | }} | ||
| + | |||
| + | '''Xylose Isomerase in Substrate and Inhibitor Michaelis States: Atomic Resolution Studies of a Metal-Mediated Hydride Shift''' | ||
| + | |||
==Overview== | ==Overview== | ||
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==About this Structure== | ==About this Structure== | ||
| - | 1S5M is a [ | + | 1S5M 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=1S5M OCA]. |
==Reference== | ==Reference== | ||
| - | Xylose isomerase in substrate and inhibitor michaelis states: atomic resolution studies of a metal-mediated hydride shift., Fenn TD, Ringe D, Petsko GA, Biochemistry. 2004 Jun 1;43(21):6464-74. PMID:[http:// | + | Xylose isomerase in substrate and inhibitor michaelis states: atomic resolution studies of a metal-mediated hydride shift., Fenn TD, Ringe D, Petsko GA, Biochemistry. 2004 Jun 1;43(21):6464-74. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/15157080 15157080] |
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Streptomyces olivochromogenes]] | [[Category: Streptomyces olivochromogenes]] | ||
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[[Category: xylose isomerase]] | [[Category: xylose isomerase]] | ||
| - | ''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 14:00:49 2008'' |
Revision as of 12:00, 20 March 2008
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| , resolution 0.98Å | |||||||
|---|---|---|---|---|---|---|---|
| Ligands: | , and | ||||||
| Gene: | XYLA (Streptomyces olivochromogenes) | ||||||
| Activity: | Xylose isomerase, with EC number 5.3.1.5 | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
Xylose Isomerase in Substrate and Inhibitor Michaelis States: Atomic Resolution Studies of a Metal-Mediated Hydride Shift
Overview
Xylose isomerase (E.C. 5.3.1.5) catalyzes the interconversion of aldose and ketose sugars and has an absolute requirement for two divalent cations at its active site to drive the hydride transfer rates of sugar isomerization. Evidence suggests some degree of metal movement at the second metal site, although how this movement may affect catalysis is unknown. The 0.95 A resolution structure of the xylitol-inhibited enzyme presented here suggests three alternative positions for the second metal ion, only one of which appears positioned in a catalytically competent manner. To complete the reaction, an active site hydroxyl species appears appropriately positioned for hydrogen transfer, as evidenced by precise bonding distances. Conversely, the 0.98 A resolution structure of the enzyme with glucose bound in the alpha-pyranose state only shows one of the metal ion conformations at the second metal ion binding site, suggesting that the linear form of the sugar is required to promote the second and third metal ion conformations. The two structures suggest a strong degree of conformational flexibility at the active site, which seems required for catalysis and may explain the poor rate of turnover for this enzyme. Further, the pyranose structure implies that His53 may act as the initial acid responsible for ring opening of the sugar to the aldose form, an observation that has been difficult to establish in previous studies. The glucose ring also appears to display significant segmented disorder in a manner suggestive of ring opening, perhaps lending insight into means of enzyme destabilization of the ground state to promote catalysis. On the basis of these results, we propose a modified version of the bridged bimetallic mechanism for hydride transfer in the case of Streptomyces olivochromogenes xylose isomerase.
About this Structure
1S5M is a Single protein structure of sequence from Streptomyces olivochromogenes. Full crystallographic information is available from OCA.
Reference
Xylose isomerase in substrate and inhibitor michaelis states: atomic resolution studies of a metal-mediated hydride shift., Fenn TD, Ringe D, Petsko GA, Biochemistry. 2004 Jun 1;43(21):6464-74. PMID:15157080
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