Amaranthus hypochondriacus and A. tricolor lectins: isolation and characterization

Asialofetuin-linked amino activated silica was used for the affinity purification of lectins from Amaranthus hypochondriacus Linn (AHL) and A. tricolor Linn (ATL). Like a few other Amaranthus lectins, these lectins were also inhibited by N-acetyl-D-galactosamine, fetuin and asialofetuin; they agglutinated human and different animal erythrocytes. The purified lectins yielded a single band on PAGE pH 8.3, pH 4.5 and SDS-PAGE, pH 8.3. These also gave a single peak in gel exclusion on Biogel P-200, HPLC 300 SW and cation exchange columns. However, both lectins gave multiple peaks in anion exchange column and multiple bands in isoelectric focusing. AHL and ATL are dimeric proteins in which the subunits having M(r) 29,000 and 39,000, respectively, are not held together by disulphide linkages. The pure lectins are glycoproteins and do not require Ca2+, Mn2+ and Mg2+ for their agglutination activity.