3thi: Difference between revisions
New page: left|200px<br /><applet load="3thi" size="450" color="white" frame="true" align="right" spinBox="true" caption="3thi, resolution 2.0Å" /> '''THIAMINASE I FROM BAC... |
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[[Image:3thi.jpg|left|200px]]<br /><applet load="3thi" size=" | [[Image:3thi.jpg|left|200px]]<br /><applet load="3thi" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="3thi, resolution 2.0Å" /> | caption="3thi, resolution 2.0Å" /> | ||
'''THIAMINASE I FROM BACILLUS THIAMINOLYTICUS'''<br /> | '''THIAMINASE I FROM BACILLUS THIAMINOLYTICUS'''<br /> | ||
==Overview== | ==Overview== | ||
Thiaminase-I catalyzes the replacement of the thiazole moiety of thiamin | Thiaminase-I catalyzes the replacement of the thiazole moiety of thiamin with a wide variety of nucleophiles, such as pyridine, aniline, catechols, quinoline, and cysteine. The crystal structure of the enzyme from Bacillus thiaminolyticus was determined at 2.5 A resolution by multiple isomorphous replacement and refined to an R factor of 0.195 (Rfree = 0.272). Two other structures, one native and one containing a covalently bound inhibitor, were determined at 2.0 A resolution by molecular replacement from a second crystal form and were refined to R factors of 0.205 and 0.217 (Rfree = 0.255 and 0.263), respectively. The overall structure contains two alpha/beta-type domains separated by a large cleft. At the base of the cleft lies Cys113, previously identified as a key active site nucleophile. The structure with a covalently bound thiamin analogue, which functions as a mechanism-based inactivating agent, confirms the location of the active site. Glu241 appears to function as an active site base to increase the nucleophilicity of Cys113. The mutant Glu241Gln was made and shows no activity. Thiaminase-I shows no sequence identity to other proteins in the sequence databases, but the three-dimensional structure shows very high structural homology to the periplasmic binding proteins and the transferrins. | ||
==About this Structure== | ==About this Structure== | ||
3THI is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacillus_subtilis Bacillus subtilis] with SO4 as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Thiamine_pyridinylase Thiamine pyridinylase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.5.1.2 2.5.1.2] Full crystallographic information is available from [http:// | 3THI is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacillus_subtilis Bacillus subtilis] with <scene name='pdbligand=SO4:'>SO4</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Thiamine_pyridinylase Thiamine pyridinylase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.5.1.2 2.5.1.2] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3THI OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Thiamine pyridinylase]] | [[Category: Thiamine pyridinylase]] | ||
[[Category: Begley, T | [[Category: Begley, T P.]] | ||
[[Category: Campobasso, N.]] | [[Category: Campobasso, N.]] | ||
[[Category: Ealick, S | [[Category: Ealick, S E.]] | ||
[[Category: SO4]] | [[Category: SO4]] | ||
[[Category: thiamin degradation]] | [[Category: thiamin degradation]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 19:11:31 2008'' | ||
Revision as of 20:11, 21 February 2008
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THIAMINASE I FROM BACILLUS THIAMINOLYTICUS
OverviewOverview
Thiaminase-I catalyzes the replacement of the thiazole moiety of thiamin with a wide variety of nucleophiles, such as pyridine, aniline, catechols, quinoline, and cysteine. The crystal structure of the enzyme from Bacillus thiaminolyticus was determined at 2.5 A resolution by multiple isomorphous replacement and refined to an R factor of 0.195 (Rfree = 0.272). Two other structures, one native and one containing a covalently bound inhibitor, were determined at 2.0 A resolution by molecular replacement from a second crystal form and were refined to R factors of 0.205 and 0.217 (Rfree = 0.255 and 0.263), respectively. The overall structure contains two alpha/beta-type domains separated by a large cleft. At the base of the cleft lies Cys113, previously identified as a key active site nucleophile. The structure with a covalently bound thiamin analogue, which functions as a mechanism-based inactivating agent, confirms the location of the active site. Glu241 appears to function as an active site base to increase the nucleophilicity of Cys113. The mutant Glu241Gln was made and shows no activity. Thiaminase-I shows no sequence identity to other proteins in the sequence databases, but the three-dimensional structure shows very high structural homology to the periplasmic binding proteins and the transferrins.
About this StructureAbout this Structure
3THI is a Single protein structure of sequence from Bacillus subtilis with as ligand. Active as Thiamine pyridinylase, with EC number 2.5.1.2 Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of thiaminase-I from Bacillus thiaminolyticus at 2.0 A resolution., Campobasso N, Costello CA, Kinsland C, Begley TP, Ealick SE, Biochemistry. 1998 Nov 10;37(45):15981-9. PMID:9843405
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