Open AccessEnergetics of 5‐bromo‐4‐chloro‐3‐indolyl‐α‐ d ‐mannose binding to the Parkia platycephala seed lectin and its use for MAD phasing
Author(s) -
Gallego del Sol Francisca,
Gómez Javier,
Hoos Sylviane,
Nagano Celso S.,
Cavada Benildo S.,
England Patrick,
Calvete Juan J.
Publication year - 2005
Publication title -
acta crystallographica section f
Language(s) - English
Resource type - Journals
ISSN - 1744-3091
DOI - 10.1107/s1744309105004835
Subject(s) - lectin , isothermal titration calorimetry , mannose , chemistry , monosaccharide , mannan binding lectin , stereochemistry , biochemistry , crystallography
Parkia platycephala belongs to the most primitive group of Leguminosae plants. Its seed lectin is made up of three homologous β‐prism repeats and exhibits binding specificity for mannose/glucose. The properties of the association between the lectin from P. platycephala seeds and monosaccharide ligands were analysed by isothermal titration calorimetry and surface plasmon resonance. The results are consistent with the lectin bearing three thermodynamically identical binding sites for mannose/glucose per monomer with dissociation constants in the millimolar range. Binding of each ligand by the lectin is enthalpically driven. Crystals have been obtained of the lectin in complex with a brominated derivative of mannose (5‐bromo‐4‐chloro‐3‐indolyl‐α‐ d ‐mannose), which were suitable for deriving an electron‐density map by MAD phasing. In agreement with the thermodynamic data, six Br atoms were found in the asymmetric unit of the monoclinic P 2 1 crystals, which contained two P. platycephala lectin molecules. The availability of other Br derivatives of monosaccharides (glucose, galactose, fucose) may make this strategy widely useful for structure elucidation of novel lectins or when (as in the case of the P. platycephala lectin) molecular‐replacement methods fail.