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==== | ==X-ray structure of the complex between human alpha thrombin and a thrombin binding aptamer variant (TBA-3Leu), which contains leucyl amide in the side chain of Thy3 at N3.== | ||
<StructureSection load='6z8x' size='340' side='right'caption='[[6z8x]]' scene=''> | <StructureSection load='6z8x' size='340' side='right'caption='[[6z8x]], [[Resolution|resolution]] 2.53Å' scene=''> | ||
== Structural highlights == | == Structural highlights == | ||
<table><tr><td colspan='2'>Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id= OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol= FirstGlance]. <br> | <table><tr><td colspan='2'>[[6z8x]] is a 3 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] and [https://en.wikipedia.org/wiki/Synthetic_construct Synthetic construct]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6Z8X OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6Z8X FirstGlance]. <br> | ||
</td></tr><tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=6z8x FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6z8x OCA], [https://pdbe.org/6z8x PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6z8x RCSB], [https://www.ebi.ac.uk/pdbsum/6z8x PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6z8x ProSAT]</span></td></tr> | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.53Å</td></tr> | ||
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=0G6:D-PHENYLALANYL-N-[(2S,3S)-6-{[AMINO(IMINIO)METHYL]AMINO}-1-CHLORO-2-HYDROXYHEXAN-3-YL]-L-PROLINAMIDE'>0G6</scene>, <scene name='pdbligand=K:POTASSIUM+ION'>K</scene>, <scene name='pdbligand=NA:SODIUM+ION'>NA</scene>, <scene name='pdbligand=QCE:[(2~{R},3~{S},5~{R})-5-[5-methyl-3-[2-(methylamino)-2-oxidanylidene-ethyl]-2,4-bis(oxidanylidene)pyrimidin-1-yl]-3-oxidanyl-oxolan-2-yl]methyl+dihydrogen+phosphite'>QCE</scene></td></tr> | |||
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=6z8x FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6z8x OCA], [https://pdbe.org/6z8x PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6z8x RCSB], [https://www.ebi.ac.uk/pdbsum/6z8x PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6z8x ProSAT]</span></td></tr> | |||
</table> | </table> | ||
== Disease == | |||
[https://www.uniprot.org/uniprot/THRB_HUMAN THRB_HUMAN] Defects in F2 are the cause of factor II deficiency (FA2D) [MIM:[https://omim.org/entry/613679 613679]. It is a very rare blood coagulation disorder characterized by mucocutaneous bleeding symptoms. The severity of the bleeding manifestations correlates with blood factor II levels.<ref>PMID:14962227</ref> <ref>PMID:6405779</ref> <ref>PMID:3771562</ref> <ref>PMID:3567158</ref> <ref>PMID:3801671</ref> <ref>PMID:3242619</ref> <ref>PMID:2719946</ref> <ref>PMID:1354985</ref> <ref>PMID:1421398</ref> <ref>PMID:1349838</ref> <ref>PMID:7865694</ref> <ref>PMID:7792730</ref> Genetic variations in F2 may be a cause of susceptibility to ischemic stroke (ISCHSTR) [MIM:[https://omim.org/entry/601367 601367]; also known as cerebrovascular accident or cerebral infarction. A stroke is an acute neurologic event leading to death of neural tissue of the brain and resulting in loss of motor, sensory and/or cognitive function. Ischemic strokes, resulting from vascular occlusion, is considered to be a highly complex disease consisting of a group of heterogeneous disorders with multiple genetic and environmental risk factors.<ref>PMID:15534175</ref> Defects in F2 are the cause of thrombophilia due to thrombin defect (THPH1) [MIM:[https://omim.org/entry/188050 188050]. It is a multifactorial disorder of hemostasis characterized by abnormal platelet aggregation in response to various agents and recurrent thrombi formation. Note=A common genetic variation in the 3-prime untranslated region of the prothrombin gene is associated with elevated plasma prothrombin levels and an increased risk of venous thrombosis. Defects in F2 are associated with susceptibility to pregnancy loss, recurrent, type 2 (RPRGL2) [MIM:[https://omim.org/entry/614390 614390]. A common complication of pregnancy, resulting in spontaneous abortion before the fetus has reached viability. The term includes all miscarriages from the time of conception until 24 weeks of gestation. Recurrent pregnancy loss is defined as 3 or more consecutive spontaneous abortions.<ref>PMID:11506076</ref> | |||
== Function == | |||
[https://www.uniprot.org/uniprot/THRB_HUMAN THRB_HUMAN] Thrombin, which cleaves bonds after Arg and Lys, converts fibrinogen to fibrin and activates factors V, VII, VIII, XIII, and, in complex with thrombomodulin, protein C. Functions in blood homeostasis, inflammation and wound healing.<ref>PMID:2856554</ref> | |||
<div style="background-color:#fffaf0;"> | |||
== Publication Abstract from PubMed == | |||
Post-SELEX modification of DNA aptamers is an established strategy to improve their affinity or inhibitory characteristics. In this study, we examined the possibility of increasing the recognition interface between the thrombin-binding aptamer HD1 (TBA) and thrombin by adding a chemically modified side chain to selected nucleotide residues. A panel of 22 TBA variants with N3-modified residues T3 and T12 was prepared by a two-step modification procedure. Aptamers were characterized by a combination of biophysical and biochemical methods. We identified mutants with enhanced affinity and improved anticoagulant activity. The crystal structures of thrombin complexes with three selected modified variants revealed that the modified pyrimidine base invariably allocates in proximity to thrombin residues Tyr76 and Ile82 due to the directing role of the unmodified TT loop. The modifications induced an increase in the contact areas between thrombin and the modified TBAs. Comparative analysis of the structural, biochemical, and biophysical data suggests that the non-equivalent binding modes of the mutants with thrombin in the T3- and T12-modified series account for the observed systematic differences in their affinity characteristics. In this study, we show that extending the recognition surface between the protein and modified aptamers is a promising approach that may improve characteristics of aptamer ligands. | |||
Expanding the recognition interface of the thrombin-binding aptamer HD1 through modification of residues T3 and T12.,Smirnov I, Kolganova N, Troisi R, Sica F, Timofeev E Mol Ther Nucleic Acids. 2021 Jan 16;23:863-871. doi: 10.1016/j.omtn.2021.01.004. , eCollection 2021 Mar 5. PMID:33614235<ref>PMID:33614235</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
</div> | |||
<div class="pdbe-citations 6z8x" style="background-color:#fffaf0;"></div> | |||
==See Also== | |||
*[[Thrombin 3D Structures|Thrombin 3D Structures]] | |||
== References == | |||
<references/> | |||
__TOC__ | __TOC__ | ||
</StructureSection> | </StructureSection> | ||
[[Category: Homo sapiens]] | |||
[[Category: Large Structures]] | [[Category: Large Structures]] | ||
[[Category: | [[Category: Synthetic construct]] | ||
[[Category: Sica F]] | |||
[[Category: Timofeev EN]] | |||
[[Category: Troisi R]] | |||