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==HIGH-RESOLUTION STRUCTURE OF ASCARIS TRYPSIN INHIBITOR IN SOLUTION: DIRECT EVIDENCE FOR A PH INDUCED CONFORMATIONAL TRANSITION IN THE REACTIVE SITE== | |||
<StructureSection load='1atd' size='340' side='right'caption='[[1atd]]' scene=''> | |||
| | == Structural highlights == | ||
| | <table><tr><td colspan='2'>[[1atd]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Ascaris_suum Ascaris suum]. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1ATD OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1ATD FirstGlance]. <br> | ||
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Solution NMR, 32 models</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=1atd FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1atd OCA], [https://pdbe.org/1atd PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1atd RCSB], [https://www.ebi.ac.uk/pdbsum/1atd PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1atd ProSAT]</span></td></tr> | |||
</table> | |||
== Function == | |||
[https://www.uniprot.org/uniprot/ITR1_ASCSU ITR1_ASCSU] | |||
== 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/at/1atd_consurf.spt"</scriptWhenChecked> | |||
<scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview03.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=1atd ConSurf]. | |||
<div style="clear:both"></div> | |||
<div style="background-color:#fffaf0;"> | |||
== Publication Abstract from PubMed == | |||
BACKGROUND: The Ascaris trypsin inhibitor (ATI) is a member of a new family of serine protease inhibitors isolated from the helminthic worm Ascaris lumbricoides var suum. This family comprises five chymotrypsin/elastase inhibitors and one trypsin inhibitor. Members are characterized by the presence of five disulfide bonds (two of which are located on either side of the reactive site) in a single small protein domain of 61-62 residues. RESULTS: The solution structure of ATI has been determined at pH 2.4 and pH 4.75 by NMR spectroscopy. Iterative refinement permitted the unambiguous assignment of the pairing of the five disulfide bridges (Cys5-Cys38, Cys15-Cys33, Cys18-Cys29, Cys22-Cys60, and Cys40-Cys54) which were previously unknown. The structure includes four short beta-strands arranged in two approximately perpendicular beta-sheets. The reactive site loop is bounded by two disulfide bridges (Cys15-Cys33 and Cys18-Cys29) and is part of the long loop (residues 15-25) connecting strands beta 1 and beta 2. Comparison of the nuclear Overhauser enhancement data at the two pH values revealed significant differences centered around the reactive site. While the reactive site at pH 2.4 closely resembles that of other protease inhibitors, at pH 4.75 the reactive site loop undergoes a major conformational rearrangement involving the psi backbone torsion angles of the P2, P1 and P1' residues (residues 30-32). This is associated with a change in the positions of the side chains of Arg31 and Glu32. CONCLUSIONS: The overall three-dimensional structure of ATI posesses an unusual fold and, with the exception of the reactive site, shows no similarity to other serine protease inhibitors. The observation that the reactive site of the low pH form of ATI is similar to that of other serine proteases suggests that this is the active form of the protein. | |||
High-resolution structure of Ascaris trypsin inhibitor in solution: direct evidence for a pH-induced conformational transition in the reactive site.,Grasberger BL, Clore GM, Gronenborn AM Structure. 1994 Jul 15;2(7):669-78. PMID:7922043<ref>PMID:7922043</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
</div> | |||
<div class="pdbe-citations 1atd" style="background-color:#fffaf0;"></div> | |||
== | ==See Also== | ||
*[[Trypsin inhibitor 3D structures|Trypsin inhibitor 3D structures]] | |||
== References == | |||
== | <references/> | ||
__TOC__ | |||
</StructureSection> | |||
[[Category: Ascaris suum]] | [[Category: Ascaris suum]] | ||
[[Category: | [[Category: Large Structures]] | ||
[[Category: Clore | [[Category: Clore GM]] | ||
[[Category: Grasberger | [[Category: Grasberger BL]] | ||
[[Category: Gronenborn | [[Category: Gronenborn AM]] | ||
Latest revision as of 10:11, 9 October 2024
HIGH-RESOLUTION STRUCTURE OF ASCARIS TRYPSIN INHIBITOR IN SOLUTION: DIRECT EVIDENCE FOR A PH INDUCED CONFORMATIONAL TRANSITION IN THE REACTIVE SITEHIGH-RESOLUTION STRUCTURE OF ASCARIS TRYPSIN INHIBITOR IN SOLUTION: DIRECT EVIDENCE FOR A PH INDUCED CONFORMATIONAL TRANSITION IN THE REACTIVE SITE
Structural highlights
FunctionEvolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedBACKGROUND: The Ascaris trypsin inhibitor (ATI) is a member of a new family of serine protease inhibitors isolated from the helminthic worm Ascaris lumbricoides var suum. This family comprises five chymotrypsin/elastase inhibitors and one trypsin inhibitor. Members are characterized by the presence of five disulfide bonds (two of which are located on either side of the reactive site) in a single small protein domain of 61-62 residues. RESULTS: The solution structure of ATI has been determined at pH 2.4 and pH 4.75 by NMR spectroscopy. Iterative refinement permitted the unambiguous assignment of the pairing of the five disulfide bridges (Cys5-Cys38, Cys15-Cys33, Cys18-Cys29, Cys22-Cys60, and Cys40-Cys54) which were previously unknown. The structure includes four short beta-strands arranged in two approximately perpendicular beta-sheets. The reactive site loop is bounded by two disulfide bridges (Cys15-Cys33 and Cys18-Cys29) and is part of the long loop (residues 15-25) connecting strands beta 1 and beta 2. Comparison of the nuclear Overhauser enhancement data at the two pH values revealed significant differences centered around the reactive site. While the reactive site at pH 2.4 closely resembles that of other protease inhibitors, at pH 4.75 the reactive site loop undergoes a major conformational rearrangement involving the psi backbone torsion angles of the P2, P1 and P1' residues (residues 30-32). This is associated with a change in the positions of the side chains of Arg31 and Glu32. CONCLUSIONS: The overall three-dimensional structure of ATI posesses an unusual fold and, with the exception of the reactive site, shows no similarity to other serine protease inhibitors. The observation that the reactive site of the low pH form of ATI is similar to that of other serine proteases suggests that this is the active form of the protein. High-resolution structure of Ascaris trypsin inhibitor in solution: direct evidence for a pH-induced conformational transition in the reactive site.,Grasberger BL, Clore GM, Gronenborn AM Structure. 1994 Jul 15;2(7):669-78. PMID:7922043[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences |
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