A general method for co-crystallisation of concanavalin A with carbohydrates.

DN Moothoo, James Henderson Naismith

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

A small grid of conditions has been developed for co-crystallization of the plant lectin concanavalin A (conA) and polysaccharides. Crystals have been obtained of complexes of conA with alpha 1-2 mannobiose, 1-methyl alpha 1-2 mannobiose, fructose, a trisaccharide and a pentasaccharide. The crystals diffract to resolutions of 1.75-2.7 Angstrom using a copper rotating-anode source. The crystals are grown in the presence of polyethylene glycol 6K [10=20%(w/v)] at around pH 6.0. Optimization for each particular carbohydrate requires small adjustments in the conditions; however, all complexes give some crystalline precipitate in this limited grid. The alpha 1-2 mannobiose complex crystals diffract to 1.75 Angstrom with space group I222 and cell dimensions a = 91.7, b = 86.8, c = 66.6 Angstrom . One monomer is present in the asymmetric unit. The 1-methyl alpha 1-2 mannobioside complex crystallizes in space group P2(1)2(1)2(1), cell dimensions a = 119.7, b = 119.7, c = 68.9 Angstrom and diffract to 2.75 Angstrom. One tetramer is present in the asymmetric unit. Two crystal forms of the conA-fructose complex have been obtained. The first has space group P2(1)2(1)2(1), cell dimensions a = 121.7, b = 119.9, c = 67.3 Angstrom with a tetramer in the asymmetric unit and diffracts to 2.6 Angstrom. The second crystallizes in space group C222(1), cell dimensions a = 103.3, b = 117.9, c = 254.3 Angstrom with two dimers in the asymmetric unit and diffracts to 2.42 Angstrom. Structures and crystallization of the trisaccharide-conA and pentasaccharide-conA complexes have already been reported. In all complexes, the protein is found as a tetramer, although varying combinations of non-crystallographic and crystallographic symmetry are involved in generating the tetramer. The precise packing of the tetramer varies from crystal to crystal and it is likely that this variability facilitates crystallization.

Original languageEnglish
Pages (from-to)353-355
Number of pages3
JournalActa Crystallographica. Section D, Biological crystallography
VolumeD55
Publication statusPublished - Jan 1999

Keywords

  • ALPHA-D-GLUCOPYRANOSIDE
  • BINDING
  • CRYSTAL
  • COMPLEX

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