Purification and characterization of lectins from Vicia hirsuta

Abstract

The presence of three lectins in the seeds of Vicia hirsuta (L.) S. F. Gray, a wild‐growing vetch, was shown. The main lectin was purified to homogeneity by buffer extraction, ammonium sulfate precipitation, affinity chromatography on Sephadex G‐100 and isoelectric focusing in granulated gel. By chromatofocusing instead of isoelectric focusing the yield was increased 5‐fold. The lectin has a pi of 6.4. It is composed of large β‐subunits (Mr 19.200) and small α‐subunits (Mr 12.800) in a 1:1 ratio. The subunits can be separated on Sephadex G‐75 when equilibrated with 6 M guanidine‐HCl. The amino acid composition of the two different subunits has been determined. No sulfur‐containing amino acids are present. The lectin resembles the lectins from legumes from the same cross‐inoculation group, i.e. Lens culinaris, Lens esculenta, Pisum satiyum and several Vicia spp. by the same type of sugar specificity and amino acid composition.