1lem

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spinqualitylabelsall models 1lem, resolution 3.0Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

THE MONOSACCHARIDE BINDING SITE OF LENTIL LECTIN: AN X-RAY AND MOLECULAR MODELLING STUDY

Overview

The X-ray crystal structure of lentil lectin in complex with, alpha-D-glucopyranose has been determined by molecular replacement and, refined to an R-value of 0.20 at 3.0 A resolution. The glucose interacts, with the protein in a manner similar to that found in the mannose, complexes of concanavalin A, pea lectin and isolectin I from Lathyrus, ochrus. The complex is stabilized by a network of hydrogen bonds involving, the carbohydrate oxygens O6, O4, O3 and O5. In addition, the, alpha-D-glucopyranose residue makes van der Waals contacts with the, protein, involving the phenyl ring of Phe123 beta. The overall structure, of lentil lectin, at this resolution, does not differ significantly from, the highly refined structures of the uncomplexed lectin. Molecular docking, studies were performed with mannose and its 2-O and 3-O-m-nitro-benzyl, derivatives to explain their high affinity binding. The interactions of, the modelled mannose with lentil lectin agree well with those observed, experimentally for the protein-carbohydrate complex. The highly flexible, Me-2-O-(m-nitro-benzyl)-alpha-D-mannopyranoside and, Me-3-O-(m-nitro-benzyl)-alpha-D-mannopyranoside become conformationally, restricted upon binding to lentil lectin. For best orientations of the two, substrates in the combining site, the loss of entropy is accompanied by, the formation of a strong hydrogen bond between the nitro group and one, amino acid, Gly97 beta and Asn125 beta, respectively, along with the, establishment of van der Waals interactions between the benzyl group and, the aromatic amino acids Tyr100 beta and Trp128 beta.

About this Structure

1LEM is a Protein complex structure of sequences from Lens culinaris with GLC, CA and MN as ligands. Full crystallographic information is available from OCA.

Reference

The monosaccharide binding site of lentil lectin: an X-ray and molecular modelling study., Loris R, Casset F, Bouckaert J, Pletinckx J, Dao-Thi MH, Poortmans F, Imberty A, Perez S, Wyns L, Glycoconj J. 1994 Dec;11(6):507-17. PMID:7696853

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