THE CARBOHYDRATE-BINDING SPECIFICITY AND MOLECULAR MODELING OF CANAVALIA-MARITIMA AND DIOCLEA-GRANDIFLORA LECTINS

The carbohydrate-binding specificity of lectins from the seeds of Cana valia maritima and Dioclea grandiflora was studied by hapten-inhibitio n of haemagglutination using various sugars and sugar derivatives as i nhibitors, including N-acetylneuraminic acid and N-acetylmuramic acid. Despite some discrepancies, both lectins exhibited a very similar car bohydrate-binding specificity as previously reported for other lectins from Diocleinae (tribe Phaseoleae, sub-tribe Diocleinae). Accordingly , both lectins exhibited almost identical hydropathic profiles and the ir three-dimensional models built up fr om the atomic coordinates of C onA looked very similar. However, docking experiments of glucose and m annose in their monosaccharide-binding sites, by comparison with the C onA-mannose complex used as a model, revealed conformational changes i n side chains of the amino acid residues involved in the binding of mo nosaccharides. These results fully agree with crystallographic data sh owing that binding of specific ligands to ConA requires conformational chances of its monosaccharide-binding site.