Studies on lectins. XLVIII. Isolation and characterization of lectins from the seeds of Lathyrus odoratus L. and Lathyrus silvestris L.

Lectins from seeds of Lathyrus odoratus L. and Lathyrus silvestris L. were isolated by (NH4)2SO4 precipitation and affinity chromatography on Sephadex G-150. Both lectins were found to be homogenous by ultracentrifugation (S20,w for the L. odoratus lectin was 3.29, for the L. silvestris lectin 3.39) and by discontinuous polyacrylamide gel electrophoresis in alkaline and acidic buffer systems. The amino acid composition of both lectins is characterized by high contents of aspartic and glutamic acids and threonine. The lectin from L. odoratus seeds contains 2.5% of neutral sugar, and the lectin from L. silvestris seeds 3.1%. Amino sugars were not detected. Threonine and valine were determined as N-terminal amino acids in the case of both lectins. Both lectins contain Mn in an amount corresponding approximately to 2 atoms per molecule. The molecular weight of the isolated lectins is 53 000, as determined by thin layer gel chromatography. Both lectins consist of two types of subunits differing in their molecular weights. Both Lathyrus lectins are nonspecific in agglutination of human erythrocytes; their hemagglutinating activity is inhibited by D-mannose and D-glucose and their alpha-glycosides. The dissociation contants of complexes of the studied lectins with D-glucose and D-mannose were determined using affinity electrophoresis.