Isolation and partial characterization of a lectin from Artocarpus incisa L. seeds

A lectin was isolated from the saline extract of Artocarpus incisa seed by affinity chromatography on cross-linked Adenanthera pavonina galactomannan in 0.15 M NaCl. The lectin was also retained in a D-gal-agarose resin and had no requirements for divalent metal cations (Ca2+ and Mn2+) for activity. The lectin contains 2.1% of carbohydrate and is characterized by high contents of acidic and hydroxylated amino acids. The lectin presented two protein bands in SDS-PAGE, with M(r) 15.5 and 12 kDa, respectively, and contains no alpha-helix, 64% antiparallel beta-sheet and 21% parallel beta-sheet/beta-turn. When submitted to gel filtration in Superose 12 R (FPLC) and Superdex 75 HR 5/5 (HPLC) columns, the lectin showed an M(r) of 48-49 kDa, suggesting a tetrameric structure.