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Energetics of galactose- and glucose-aromatic amino acid interactions: implications for binding in galactose-specific proteins

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Title Energetics of galactose- and glucose-aromatic amino acid interactions: implications for binding in galactose-specific proteins
 
Creator SUJATHA, MANNARGUDI S
SASIDHAR, YELLAMRAJU U
BALAJI, PETETY V
 
Subject geometry
ab initio calculations
hydrogen bonds
amino acids
 
Description An aromatic amino acid is present in the binding site of a number of sugar binding proteins. The interaction of the saccharide with the aromatic residue is determined by their relative position as well as orientation. The position-orientation of the saccharide relative to the aromatic residue was found to vary in different sugar-binding proteins. In the present study, interaction energies of the complexes of galactose (Gal) and of glucose (Glc) with aromatic residue analogs have been calculated by ab initio density functional (U-B3LYP/6-31G**) theory. The position-orientations of the saccharide with respect to the aromatic residue observed in various Gal-, Glc- and mannose-protein complexes were chosen for the interaction energy calculations. The results of these calculations show that galactose can interact with the aromatic residue with similar interaction energies in a number of position-orientations. The interaction energy of Gal-aromatic residue analog complex in position-orientations observed for the bound saccharide in Glc/Man-protein complexes is comparable to the Glc-aromatic residue analog complex in the same position-orientation. In contrast, there is a large variation in interaction energies of complexes of Glc- and of Gal- with the aromatic residue analog in position-orientations observed in Gal-protein complexes. Furthermore, the conformation wherein the O6 atom is away from the aromatic residue is preferred for the exocyclic CH2OH group in Gal-aromatic residue analog complexes. The implications of these results for saccharide binding in Gal-specific proteins and the possible role of the aromatic amino acid to ensure proper positioning and orientation of galactose in the binding site have been discussed.
 
Publisher Cold Spring Harbor Laboratory Press
 
Date 2007-01-18T10:40:48Z
2011-11-25T11:25:34Z
2011-12-26T13:05:41Z
2011-12-27T05:52:51Z
2007-01-18T10:40:48Z
2011-11-25T11:25:34Z
2011-12-26T13:05:41Z
2011-12-27T05:52:51Z
2004
 
Type Article
 
Identifier Protein Sci., 13:2502-2514
http://hdl.handle.net/10054/40
http://dspace.library.iitb.ac.in/xmlui/handle/10054/40
 
Language en_US