Wheat-germ lectin isolation

Figure 2.18 Wheat germ lectin isolation using A -acetyl-o-glucosamine as the ligand. Chromatography conditions column, Waters API glass column, 100 x 10 mm I.D. flow rate, 1 ml/min detection, UV absorbance at 280 nm. The sample was 1 ml of crude wheat germ preparation 1.2 mg/ml of lectin was eluted from a crude preparation with 6.8 mg/ml total protein. (Reprinted from Ref. 64 with permission.)...

Wheat germ agglutinin is the most studied of these lectins and also one of the most useful in its biomedical application. The lectin is a homodimer composed of subunits of Mr = 23 600 Da which dissociates into monomers at acid pH. It is a pure, metal-free protein devoid of carbohydrate residues, which is isolated as a mixture of four isolectins differing in electrophoretic mobility [116,117]. The lectin has been sequenced (171 amino acids per polypeptide chain) and its X-ray crystallographic structure determined at a 2.0 A resolution [118,119]. 

A recent volume in Methods in Enzymology has described techniques for investigating membranes, including the use of lectins it also contains a section on the isolation and purification of wheat-germ agglutinin. ... 

Two lectins, one isolated from the horseshoe crab, Limulus poly-phemus (Pardoe and Uhlenbruck, 1970 Marchalonis and Edelman, 1968), and the other from wheat germ, Triticum vulgaris (Greenaway and LeVine, 1973 Bhavanandan and Davidson, 1975 Matsumoto and Codington, unpublished results), may attach at the cell periphery to receptor sites that include terminal glycoprotein-bound sialic acid units. The horseshoe crab lectin, purified and characterized by Marchalonis and Edelman (1968), was found by Pardoe and Uhlenbruck (1970) to be specific for terminal sialic acid residues. 

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