The structure of pea lectin-D-glucopyranose complex at a 1.9 Å resolution

The structure of a new crystal complex of pea lectin (Pisum sativum, dimer, molecular mass ca. 52 kDa) with D-glucopyranose grown by a cocrystallization procedure was determined by the molecular replacement method at a 1.9 Å resolution (space group P2₁2₁2₁, unit cell parameters a = 62.8, b = 135.2, c = 54.8 Å). After crystallographic refinement, the standard R-factor was equal to 18.7%. Coordination of captured Ca²⁺ and Mn²⁺ ions included in the protein is formed by ion-dipole interaction with four water molecules and six amino acid residues of lectin. The glucose molecule is fixed by six hydrogen bonds with Asp81, Gly99, Asn125, Ala217, and Glu218. The van der Waals contacts with the side chains of the Phe123 and Ala80 residues additionally stabilize the monosaccharide position, albeit only slightly.