About the Lectin
The lectin from the common garden pea is similar to the lentil in structure and specificity. It is a mixture of primarily two very similar isolectins that can be separated by ion exchange chromatography 1 . Although a heterodimer (α 2 β 2 ), it is the product of a single gene 2 which is cleaved into subunits of 17 kDa (β) and 6 kDa (α)3. The β subunits are identical, but the isolectins have different α subunits due to differential C-terminal cleavage 2,4 . X-Ray crystal structures of the free lectin and that complexed with a branched trimannoside have been determined 5 . Calcium is required for lectin binding, and addition of EDTA prevents lectin induced agglutination and glycoprotein precipitation 6 . Mannose dendrimers are particularly effective ligands 7 . Although mannose(or glucose) is the primary determinant for binding, α-fucosylation at the 6-position of the N-linked GlcNAc of glycoproteins promotes their binding, although terminal α6 fucosylation, such as on mouse IgM 1A , prevents binding. Also, many glycoproteins containing branched mannose structures do not react. Glycopeptides isolated from rat IgE and mouse IgM1B react well with PSA 8 . Storage proteins found in the seeds of the garden pea and the lentil react with their respective lectins by virtue of their glycosylation pattern, as well as by ionic interactions. This supports some of the theories regarding the in vivo biological roles of lectins 9 . PSA has proven to be especially valuable in the determination of acrosome status of mammalian sperm cells, either as the fluorescently labeled lectin 10 , or when attached to paramagnetic beads 11 .
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|Buffer||0.05M Tris – 0.15M NaCl, pH 7.0-7.2|
|Blood Group||Non-specific after neuraminidase treatment of the blood cells.|
|Activity||Between 10-100 μg/ml may be required to agglutinate neuraminidase treated red blood cells.|
|Inhibitory Carbohydrate||Methyl-D-mannopyranoside, D-Mannose.|
|Molecular Weight||Heterotetramer, 46 kDa; subunits of 17k Da and 6 kDa. Several bands appear by SDS-PAGE. Predominant bands are at 15, 18, 22, 25, and 50 kDa.|