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Composed of four subunits of approximately equal size, soybean agglutinin is a family of closely related isolectins. This glycoprotein has a molecular weight of about 120,000 and an isoelectric point near pH 6.0. SBA preferentially binds to oligosaccharide structures with terminal a- or b-linked N-acetylgalactosamine, and to a lesser extent, galactose residues. Binding can be blocked by substitutions on penultimate sugars, such as fucose attached to the penultimate galactose in blood group B substance. SBA has been used in glycoprotein fractionation, histochemical applications and cell sorter analysis.
An important application for SBA is the separation of pluripotential stem cells from human bone marrow. Cells fractionated by SBA do not produce graft vs host disease and can be used in bone marrow transplantation across histocompatibility barriers (references available upon request). It should be noted that some forms of SBA seem to be excellent in separating human cells while others are better for cells of other species. |