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New page: left|200px<br /><applet load="1qfd" size="450" color="white" frame="true" align="right" spinBox="true" caption="1qfd" /> '''NMR SOLUTION STRUCTURE OF ALPHA-AMYLASE INHI...
 
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[[Image:1qfd.jpg|left|200px]]<br /><applet load="1qfd" size="450" color="white" frame="true" align="right" spinBox="true"
caption="1qfd" />
'''NMR SOLUTION STRUCTURE OF ALPHA-AMYLASE INHIBITOR (AAI)'''<br />


==Overview==
==NMR SOLUTION STRUCTURE OF ALPHA-AMYLASE INHIBITOR (AAI)==
alpha-Amylase inhibitor (AAI), a 32-residue miniprotein from the Mexican, crop plant amaranth (Amaranthus hypochondriacus), is the smallest known, alpha-amylase inhibitor and is specific for insect alpha-amylases, (Chagolla-Lopez, A., Blanco-Labra, A., Patthy, A., Sanchez, R., and, Pongor, S. (1994) J. Biol. Chem. 269, 23675-23680). Its disulfide topology, was confirmed by Edman degradation, and its three-dimensional solution, structure was determined by two-dimensional 1H NMR spectroscopy at 500, MHz. Structural constraints (consisting of 348 nuclear Overhauser effect, interproton distances, 8 backbone dihedral constraints, and 9 disulfide, distance constraints) were used as an input to the X-PLOR program for, simulated annealing and energy minimization calculations. The final set of, 10 structures had a mean pairwise root mean square deviation of 0.32 A for, the backbone atoms and 1.04 A for all heavy atoms. The structure of AAI, consists of a short triple-stranded beta-sheet stabilized by three, disulfide bonds, forming a typical knottin or inhibitor cystine knot fold, found in miniproteins, which binds various macromolecular ligands. When, the first intercystine segment of AAI (sequence IPKWNR) was inserted into, a homologous position of the spider toxin Huwentoxin I, the resulting, chimera showed a significant inhibitory activity, suggesting that this, segment takes part in enzyme binding.
<StructureSection load='1qfd' size='340' side='right'caption='[[1qfd]]' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1qfd]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Amaranthus_hypochondriacus Amaranthus hypochondriacus]. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1QFD OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1QFD FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Solution NMR, 10 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=1qfd FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1qfd OCA], [https://pdbe.org/1qfd PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1qfd RCSB], [https://www.ebi.ac.uk/pdbsum/1qfd PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1qfd ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/IAAI_AMAHP IAAI_AMAHP] Alpha-amylase inhibitor. It is active against alpha-amylases from Tribolium castaneum and Prostephanus truncatus larvae.
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
alpha-Amylase inhibitor (AAI), a 32-residue miniprotein from the Mexican crop plant amaranth (Amaranthus hypochondriacus), is the smallest known alpha-amylase inhibitor and is specific for insect alpha-amylases (Chagolla-Lopez, A., Blanco-Labra, A., Patthy, A., Sanchez, R., and Pongor, S. (1994) J. Biol. Chem. 269, 23675-23680). Its disulfide topology was confirmed by Edman degradation, and its three-dimensional solution structure was determined by two-dimensional 1H NMR spectroscopy at 500 MHz. Structural constraints (consisting of 348 nuclear Overhauser effect interproton distances, 8 backbone dihedral constraints, and 9 disulfide distance constraints) were used as an input to the X-PLOR program for simulated annealing and energy minimization calculations. The final set of 10 structures had a mean pairwise root mean square deviation of 0.32 A for the backbone atoms and 1.04 A for all heavy atoms. The structure of AAI consists of a short triple-stranded beta-sheet stabilized by three disulfide bonds, forming a typical knottin or inhibitor cystine knot fold found in miniproteins, which binds various macromolecular ligands. When the first intercystine segment of AAI (sequence IPKWNR) was inserted into a homologous position of the spider toxin Huwentoxin I, the resulting chimera showed a significant inhibitory activity, suggesting that this segment takes part in enzyme binding.


==About this Structure==
Solution structure of the major alpha-amylase inhibitor of the crop plant amaranth.,Lu S, Deng P, Liu X, Luo J, Han R, Gu X, Liang S, Wang X, Li F, Lozanov V, Patthy A, Pongor S J Biol Chem. 1999 Jul 16;274(29):20473-8. PMID:10400675<ref>PMID:10400675</ref>
1QFD is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Amaranthus_hypochondriacus Amaranthus hypochondriacus]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1QFD OCA].


==Reference==
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
Solution structure of the major alpha-amylase inhibitor of the crop plant amaranth., Lu S, Deng P, Liu X, Luo J, Han R, Gu X, Liang S, Wang X, Li F, Lozanov V, Patthy A, Pongor S, J Biol Chem. 1999 Jul 16;274(29):20473-8. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=10400675 10400675]
</div>
<div class="pdbe-citations 1qfd" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Amaranthus hypochondriacus]]
[[Category: Amaranthus hypochondriacus]]
[[Category: Single protein]]
[[Category: Large Structures]]
[[Category: Deng, P.]]
[[Category: Deng P]]
[[Category: Feng, L.]]
[[Category: Feng L]]
[[Category: Gu, X.]]
[[Category: Gu X]]
[[Category: Han, R.]]
[[Category: Han R]]
[[Category: Liang, S.]]
[[Category: Liang S]]
[[Category: Liu, X.]]
[[Category: Liu X]]
[[Category: Lozanov, V.]]
[[Category: Lozanov V]]
[[Category: Lu, S.]]
[[Category: Lu S]]
[[Category: Luo, J.]]
[[Category: Luo J]]
[[Category: Patthy, A.]]
[[Category: Patthy A]]
[[Category: Pongor, S.]]
[[Category: Pongor S]]
[[Category: Wang, X.]]
[[Category: Wang X]]
[[Category: inhibitor]]
 
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