Phaseolus vulgaris lectin heterogeneity related to their metal content

The seed lectins of Phaseolus vulgaris cv. Contender typically consist of five tetrameric isolectins E₄, E₃L, E₂L₂, EL₃ and L₄. However electrophoretic and isoelectric focusing analysis of each purified protomer show a great heterogeneity. We demonstrate that each tetrameric isolectin exists in five different electrophoretic forms depending on the amount of Mn²⁺ cation bound to each isolectin. The effects of Mn²⁺ binding on charge and/or molecular properties of the protomers are discussed. Under the same experimental conditions, if we use Ca²⁺ ions instead of Mn²⁺, the abovemodifications are not observed.