1awf: Difference between revisions
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[[Image:1awf.gif|left|200px]]<br /><applet load="1awf" size=" | [[Image:1awf.gif|left|200px]]<br /><applet load="1awf" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="1awf, resolution 2.2Å" /> | caption="1awf, resolution 2.2Å" /> | ||
'''NOVEL COVALENT THROMBIN INHIBITOR FROM PLANT EXTRACT'''<br /> | '''NOVEL COVALENT THROMBIN INHIBITOR FROM PLANT EXTRACT'''<br /> | ||
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==About this Structure== | ==About this Structure== | ||
1AWF is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Hirudo_medicinalis Hirudo medicinalis] and [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with GR4 as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Thrombin Thrombin], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.4.21.5 3.4.21.5] Known structural/functional Site: <scene name='pdbsite=NUL:Catalytic Triad Of SER Proteinases'>NUL</scene>. Full crystallographic information is available from [http:// | 1AWF is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Hirudo_medicinalis Hirudo medicinalis] and [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with <scene name='pdbligand=GR4:'>GR4</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Thrombin Thrombin], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.4.21.5 3.4.21.5] Known structural/functional Site: <scene name='pdbsite=NUL:Catalytic+Triad+Of+SER+Proteinases'>NUL</scene>. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1AWF OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: trypsin like proteinase]] | [[Category: trypsin like proteinase]] | ||
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Revision as of 10:31, 3 February 2008
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NOVEL COVALENT THROMBIN INHIBITOR FROM PLANT EXTRACT
OverviewOverview
High-throughput screening of methanolic extracts from the leaves of the, plant Lantana camara identified potent inhibitors of human alpha-thrombin, which were shown to be 5,5-trans-fused cyclic lactone euphane triterpenes, [O'Neill et al. (1998) J. Nat. Prod. (submitted for publication)]., Proflavin displacement studies showed the inhibitors to bind at the active, site of alpha-thrombin and alpha-chymotrypsin. Kinetic analysis of, alpha-thrombin showed tight-binding reversible competitive inhibition by, both compounds, named GR133487 and GR133686, with respective kon values at, pH 8.4 of 1.7 x 10(6) s-1 M-1 and 4.6 x 10(6) s-1 M-1. Electrospray, ionization mass spectrometry of thrombin/inhibitor complexes showed the, tight-bound species to be covalently attached, suggesting acyl-enzyme, formation by reaction of the active-site Ser195 with the trans-lactone, carbonyl. X-ray crystal structures of alpha-thrombin/GR133686 (3.0 A, resolution) and alpha-thrombin/GR133487 (2.2 A resolution) complexes, showed continuous electron density between Ser195 and the ring-opened, lactone carbonyl, demonstrating acyl-enzyme formation. Turnover of, inhibitor by alpha-thrombin was negligible and mass spectrometry of, isolated complexes showed that reversal of inhibition occurs by, reformation of the trans-lactone from the acyl-enzyme.The catalytic triad, appears undisrupted and the inhibitor carbonyl occupies the oxyanion hole, suggesting the observed lack of turnover is due to exclusion of water for, deacylation. The acyl-enzyme inhibitor hydroxyl is properly positioned for, nucleophilic attack on the ester carbonyl and therefore relactonization;, furthermore, the higher resolution structure of alpha-thrombin/GR133487, shows this hydroxyl to be effectively superimposable with the recently, proposed deacylating water for peptide substrate hydrolysis [Wilmouth, R., C., et al. (1997) Nat. Struct.Biol. 4, 456-462], suggesting the, alpha-thrombin/GR133487 complex may be a good model for this reaction.
DiseaseDisease
Known diseases associated with this structure: Dysprothrombinemia OMIM:[176930], Hyperprothrombinemia OMIM:[176930], Hypoprothrombinemia OMIM:[176930]
About this StructureAbout this Structure
1AWF is a Protein complex structure of sequences from Hirudo medicinalis and Homo sapiens with as ligand. Active as Thrombin, with EC number 3.4.21.5 Known structural/functional Site: . Full crystallographic information is available from OCA.
ReferenceReference
Novel natural product 5,5-trans-lactone inhibitors of human alpha-thrombin: mechanism of action and structural studies., Weir MP, Bethell SS, Cleasby A, Campbell CJ, Dennis RJ, Dix CJ, Finch H, Jhoti H, Mooney CJ, Patel S, Tang CM, Ward M, Wonacott AJ, Wharton CW, Biochemistry. 1998 May 12;37(19):6645-57. PMID:9578548
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