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== | ==CRYSTAL STRUCTURE OF A1PI-PITTSBURGH IN THE NATIVE CONFORMATION== | ||
<StructureSection load='1oo8' size='340' side='right'caption='[[1oo8]], [[Resolution|resolution]] 2.65Å' scene=''> | |||
== Structural highlights == | |||
<table><tr><td colspan='2'>[[1oo8]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1OO8 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1OO8 FirstGlance]. <br> | |||
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.65Å</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=1oo8 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1oo8 OCA], [https://pdbe.org/1oo8 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1oo8 RCSB], [https://www.ebi.ac.uk/pdbsum/1oo8 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1oo8 ProSAT]</span></td></tr> | |||
</table> | |||
== Disease == | |||
[https://www.uniprot.org/uniprot/A1AT_HUMAN A1AT_HUMAN] Defects in SERPINA1 are the cause of alpha-1-antitrypsin deficiency (A1ATD) [MIM:[https://omim.org/entry/613490 613490]. A disorder whose most common manifestation is emphysema, which becomes evident by the third to fourth decade. A less common manifestation of the deficiency is liver disease, which occurs in children and adults, and may result in cirrhosis and liver failure. Environmental factors, particularly cigarette smoking, greatly increase the risk of emphysema at an earlier age.<ref>PMID:1905728</ref> <ref>PMID:2390072</ref> <ref>PMID:2227940</ref> | |||
== Function == | |||
[https://www.uniprot.org/uniprot/A1AT_HUMAN A1AT_HUMAN] Inhibitor of serine proteases. Its primary target is elastase, but it also has a moderate affinity for plasmin and thrombin. Irreversibly inhibits trypsin, chymotrypsin and plasminogen activator. The aberrant form inhibits insulin-induced NO synthesis in platelets, decreases coagulation time and has proteolytic activity against insulin and plasmin.[:]<ref>PMID:1906855</ref> <ref>PMID:1406456</ref> Short peptide from AAT: reversible chymotrypsin inhibitor. It also inhibits elastase, but not trypsin. Its major physiological function is the protection of the lower respiratory tract against proteolytic destruction by human leukocyte elastase (HLE).[:]<ref>PMID:1906855</ref> <ref>PMID:1406456</ref> | |||
== Evolutionary Conservation == | |||
[[Image:Consurf_key_small.gif|200px|right]] | |||
Check<jmol> | |||
<jmolCheckbox> | |||
<scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/oo/1oo8_consurf.spt"</scriptWhenChecked> | |||
<scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked> | |||
<text>to colour the structure by Evolutionary Conservation</text> | |||
</jmolCheckbox> | |||
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=1oo8 ConSurf]. | |||
<div style="clear:both"></div> | |||
<div style="background-color:#fffaf0;"> | |||
== Publication Abstract from PubMed == | |||
The serpin antithrombin is a slow thrombin inhibitor that requires heparin to enhance its reaction rate. In contrast, alpha1-proteinase inhibitor (alpha1PI) Pittsburgh (P1 Met --> Arg natural variant) inhibits thrombin 17 times faster than pentasaccharide heparin-activated antithrombin. We present here x-ray structures of free and S195A trypsin-bound alpha1PI Pittsburgh, which show that the reactive center loop (RCL) possesses a canonical conformation in the free serpin that does not change upon binding to S195A trypsin and that contacts the proteinase only between P2 and P2'. By inference from the structure of heparin cofactor II bound to S195A thrombin, this RCL conformation is also appropriate for binding to thrombin. Reaction rates of trypsin and thrombin with alpha1PI Pittsburgh and antithrombin and their P2 variants show that the low antithrombin-thrombin reaction rate results from the antithrombin RCL sequence at P2 and implies that, in solution, the antithrombin RCL must be in a similar canonical conformation to that found here for alpha1PI Pittsburgh, even in the nonheparin-activated state. This suggests a general, limited, canonical-like interaction between serpins and proteinases in their Michaelis complexes. | The serpin antithrombin is a slow thrombin inhibitor that requires heparin to enhance its reaction rate. In contrast, alpha1-proteinase inhibitor (alpha1PI) Pittsburgh (P1 Met --> Arg natural variant) inhibits thrombin 17 times faster than pentasaccharide heparin-activated antithrombin. We present here x-ray structures of free and S195A trypsin-bound alpha1PI Pittsburgh, which show that the reactive center loop (RCL) possesses a canonical conformation in the free serpin that does not change upon binding to S195A trypsin and that contacts the proteinase only between P2 and P2'. By inference from the structure of heparin cofactor II bound to S195A thrombin, this RCL conformation is also appropriate for binding to thrombin. Reaction rates of trypsin and thrombin with alpha1PI Pittsburgh and antithrombin and their P2 variants show that the low antithrombin-thrombin reaction rate results from the antithrombin RCL sequence at P2 and implies that, in solution, the antithrombin RCL must be in a similar canonical conformation to that found here for alpha1PI Pittsburgh, even in the nonheparin-activated state. This suggests a general, limited, canonical-like interaction between serpins and proteinases in their Michaelis complexes. | ||
Canonical inhibitor-like interactions explain reactivity of alpha1-proteinase inhibitor Pittsburgh and antithrombin with proteinases.,Dementiev A, Simonovic M, Volz K, Gettins PG J Biol Chem. 2003 Sep 26;278(39):37881-7. Epub 2003 Jul 14. PMID:12860985<ref>PMID:12860985</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
</div> | |||
<div class="pdbe-citations 1oo8" style="background-color:#fffaf0;"></div> | |||
== | ==See Also== | ||
*[[Alpha-1-antitrypsin 3D structures|Alpha-1-antitrypsin 3D structures]] | |||
== References == | |||
<references/> | |||
__TOC__ | |||
</StructureSection> | |||
[[Category: Homo sapiens]] | [[Category: Homo sapiens]] | ||
[[Category: | [[Category: Large Structures]] | ||
[[Category: Dementiev | [[Category: Dementiev A]] | ||
[[Category: Gettins | [[Category: Gettins PG]] | ||
[[Category: Simonovic | [[Category: Simonovic M]] | ||
[[Category: Volz | [[Category: Volz K]] | ||