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| {{STRUCTURE_1qfd| PDB=1qfd | SCENE= }} | | {{STRUCTURE_1qfd| PDB=1qfd | SCENE= }} |
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| '''NMR SOLUTION STRUCTURE OF ALPHA-AMYLASE INHIBITOR (AAI)'''
| | ===NMR SOLUTION STRUCTURE OF ALPHA-AMYLASE INHIBITOR (AAI)=== |
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| ==Overview==
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| 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.
| | The line below this paragraph, {{ABSTRACT_PUBMED_10400675}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 10400675 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_10400675}} |
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| ==About this Structure== | | ==About this Structure== |
| 1QFD is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Amaranthus_hypochondriacus Amaranthus hypochondriacus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1QFD OCA]. | | 1QFD is a [[Single protein]] structure of sequence from [http://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]. |
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| ==Reference== | | ==Reference== |
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| [[Category: Wang, X.]] | | [[Category: Wang, X.]] |
| [[Category: Inhibitor]] | | [[Category: Inhibitor]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 06:12:05 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 23:31:06 2008'' |
