1QFD
NMR SOLUTION STRUCTURE OF ALPHA-AMYLASE INHIBITOR (AAI)
Summary for 1QFD
| Entry DOI | 10.2210/pdb1qfd/pdb |
| NMR Information | BMRB: 4490 |
| Descriptor | PROTEIN (ALPHA-AMYLASE INHIBITOR) (1 entity in total) |
| Functional Keywords | inhibitor |
| Biological source | Amaranthus hypochondriacus (grain amaranth) |
| Total number of polymer chains | 1 |
| Total formula weight | 3595.11 |
| Authors | Lu, S.,Deng, P.,Liu, X.,Luo, J.,Han, R.,Gu, X.,Liang, S.,Wang, X.,Feng, L.,Lozanov, V.,Patthy, A.,Pongor, S. (deposition date: 1999-04-08, release date: 1999-07-16, Last modification date: 2024-10-16) |
| Primary citation | Lu, S.,Deng, P.,Liu, X.,Luo, J.,Han, R.,Gu, X.,Liang, S.,Wang, X.,Li, F.,Lozanov, V.,Patthy, A.,Pongor, S. Solution structure of the major alpha-amylase inhibitor of the crop plant amaranth. J.Biol.Chem., 274:20473-20478, 1999 Cited by PubMed Abstract: 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. PubMed: 10400675DOI: 10.1074/jbc.274.29.20473 PDB entries with the same primary citation |
| Experimental method | SOLUTION NMR |
Structure validation
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