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Brazilian Journal of Plant Physiology
On-line version ISSN 1677-9452
MELGAREJO, Luz Marina; VEGA, Nohora and PEREZ, Gerardo. Isolation and characterization of novel lectins from Canavalia ensiformis DC and Dioclea grandiflora Mart. ex Benth. seeds. Braz. J. Plant Physiol. [online]. 2005, vol.17, n.3, pp. 315-324. ISSN 1677-9452. http://dx.doi.org/10.1590/S1677-04202005000300006.
Two lectins were isolated from Canavalia ensiformis and Dioclea grandiflora seeds. Gel filtration produced a fraction corresponding to Con A or D. grandiflora lectin while erythroagglutination assays revealed a distinct fraction presenting a lectin that agglutinates human red blood cells (RBCs) but not rabbit RBCs. Hydrophobic interaction chromatography showed that the latter fraction yielded a protein that readily agglutinates human erythrocytes; the lectin was also purified by affinity chromatography on Lac-Sepharose showing similar properties to that of the Phenyl-Sepharose-purified lectin. Despite minor differences (carbohydrate content or A1%1cm), the two lectins showed similar molecular properties in that they consisted of two non-covalently linked monomers having a Mr of 29-30 kDa and their pI values indicated that both lectins were slightly acidic proteins. The C. ensiformis lectin (CEL-II) and D. grandiflora lectin (DGL-II) specifically recognised the H-type 2 blood group (a-L-Fuc (1-2)-b-D-Gal (1-4)-b-D-GlcNAc-O-R), while binding to H-type 1, H-type 3, H-type 4, Leª or Ley was weaker. Carbohydrate inhibition of erythroagglutination showed that simple sugars were weakly recognised by the lectins, if at all. The N-terminal region presented a unique sequence hitherto found only in some Diocleinae lectins (designated type II). The overall results confirmed the existence of a second distinct lectin type, phylogenetically close to Diocleinae species. The data indicate a functional similarity among lectins of this type which possesses distinctive characteristics differentiating them from "classical" Man/Glc lectins.
Keywords : Diocleinae; Leguminoseae; characterization; lectins.