Structure of ligand-free maltodextrin-binding protein

Experimental Data Snapshot

  • Resolution: 2.00 Å
  • R-Value Free: 0.260 
  • R-Value Work: 0.200 

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Structural evidence for a dominant role of nonpolar interactions in the binding of a transport/chemosensory receptor to its highly polar ligands.

Duan, X.Quiocho, F.A.

(2002) Biochemistry 41: 706-712

  • DOI: https://doi.org/10.1021/bi015784n
  • Primary Citation of Related Structures:  
    1EZ9, 1JW4, 1JW5

  • PubMed Abstract: 

    The receptor, a maltose/maltooligosaccharide-binding protein, has been found to be an excellent system for the study of molecular recognition because its polar and nonpolar binding functions are segregated into two globular domains. The X-ray structures of the "closed" and "open" forms of the protein complexed with maltose and maltotetraitol have been determined. These sugars have approximately 3 times more accessible polar surface (from OH groups) than nonpolar surface (from small clusters of sugar ring CH bonds). In the closed structures, the oligosaccharides are buried in the groove between the two domains of the protein and bound by extensive hydrogen bonding interactions of the OH groups with the polar residues confined mostly in one domain and by nonpolar interactions of the CH clusters with four aromatic residues lodged in the other domain. Substantial contacts between the sugar hydroxyls and aromatic residues are also formed. In the open structures, the oligosaccharides are bound almost exclusively in the domain rich in aromatic residues. This finding, along with the analysis of buried surface area due to complex formations in the open and closed structures, supports a major role for nonpolar interactions in initial ligand binding even when the ligands have significantly greater potential for highly specific polar interactions.

  • Organizational Affiliation

    Howard Hughes Medical Institute and Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
maltodextrin-binding protein370Escherichia coliMutation(s): 0 
Find proteins for P0AEX9 (Escherichia coli (strain K12))
Explore P0AEX9 
Go to UniProtKB:  P0AEX9
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP0AEX9
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.00 Å
  • R-Value Free: 0.260 
  • R-Value Work: 0.200 
  • Space Group: P 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 38.1α = 99.6
b = 44.6β = 101.6
c = 58.3γ = 104.5
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2002-01-30
    Type: Initial release
  • Version 1.1: 2008-04-27
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2018-02-14
    Changes: Experimental preparation
  • Version 1.4: 2024-02-07
    Changes: Data collection, Database references