Isolation and partial characterization of two isolectins from Lathyrus ochrus (L.) DC. seeds

Two isolectins have been isolated from Lathyrus ochrus (L.) DC. seeds by ammonium sulfate precipitation, affinity chromatography on Sephadex G-100 and subsequent chromatofocusing. The isolectins, whose isoelectric points are respectively pH 7.2 and pH 6.0, have a relative molecular mass about 49 000 and are tetramers consisting of two slightly different kinds of light (M_r 4500) and heavy (M_r 20 000) subunits. The amino acid composition, N-terminal amino acids, carbohydrate and metal content of both the isolectins and their subunits have been compared. The isolectins are non-specific in hemagglutination and agglutinate equally well human erythrocytes of different ABO groups. Their hemagglutinating activity is inhibited best by D-mannose, D-glucose and their α-methylglucosides derivatives. They share antigenic determinants in common with other Lathyrus lectins and other lectins belonging to the Vicieae tribe.