Biological Assembly 1  

 3D View: Structure | 1D-3D View | Validation Report

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A1 

Biological assembly 1 assigned by authors.

Macromolecule Content

• Total Structure Weight: 3.60 kDa 
• Atom Count: 246 
• Modelled Residue Count: 32 
• Deposited Residue Count: 32 
• Unique protein chains: 1

1QFD

NMR SOLUTION STRUCTURE OF ALPHA-AMYLASE INHIBITOR (AAI)

• PDB DOI: 10.2210/pdb1QFD/pdb
• BMRB: 4404
• BMRB: 4490

• Classification: INHIBITOR
• Organism(s): Amaranthus hypochondriacus
• Mutation(s): No 


• Deposited: 1999-04-08 Released: 1999-07-16 
• Deposition Author(s): Lu, S., Deng, P., Liu, X., Luo, J., Han, R., Gu, X., Liang, S., Wang, X., Feng, L., Lozanov, V., Patthy, A., Pongor, S.

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Experimental Data Snapshot

• Method: SOLUTION NMR
• Conformers Calculated: 50 
• Conformers Submitted: 10 
• Selection Criteria: LEAST RESTRAINT VIOLATION AND RESULT OF PROCHECK 

Literature

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.

(1999) J Biol Chem 274: 20473-20478

• PubMed: 10400675 
• DOI: 10.1074/jbc.274.29.20473
• Primary Citation of Related Structures:  
  1QFD


• 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.

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Related Citations: 

• Synthesis and Cystine/Cysteine-Catalyzed Oxidative Folding of the Amaranth Alpha-Amylase Inhibitor
  Lozanov, V., Guarnaccia, C., Patthy, A., Foti, S., Pongor, S.
  (1997) J Pept Res 50(1: 65

• A Novel Alpha-Amylase Inhibitor from Amaranth (Amaranthus Hypocondriacus)Seeds
  Chagolla-Lopez, A., Blanco-Labra, A., Patthy, A., Sanchez, R., Pongor, S.
  (1994) J Biol Chem 269: 23675

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Organizational Affiliation: 

Peking University, Beijing 100871, China.

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
PROTEIN (ALPHA-AMYLASE INHIBITOR)	A	32	Amaranthus hypochondriacus	Mutation(s): 0  Gene Names: AAI
UniProt
Find proteins for P80403 (Amaranthus hypochondriacus) Explore P80403  Go to UniProtKB:  P80403

Experimental Data & Validation

Experimental Data

• Method: SOLUTION NMR
• Conformers Calculated: 50 
• Conformers Submitted: 10 
• Selection Criteria: LEAST RESTRAINT VIOLATION AND RESULT OF PROCHECK 
• OLDERADO: 1QFD Olderado

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 1999-04-08 
• Released Date: 1999-07-16 
Deposition Author(s): Lu, S., Deng, P., Liu, X., Luo, J., Han, R., Gu, X., Liang, S., Wang, X., Feng, L., Lozanov, V., Patthy, A., Pongor, S.

Revision History  

• Version 1.0: 1999-07-16
  Type: Initial release
  
• Version 1.1: 2007-10-21
  Changes: Version format compliance
• Version 1.2: 2011-07-13
  Changes: Version format compliance
• Version 1.3: 2017-11-29
  Changes: Derived calculations