Lectins affinity adsorbents

Affinity adsorbents having carbohydrate ligands have been used for the isolation and purification of many types of macromolecular substances. To illustrate, several types of antibodies, enzymes, lectins, and myeloma proteins have been obtained in highly purified form. All of the substances that have been purified by this procedure exhibit specificity for a particular carbohydrate moiety. It is the purpose of this article to assemble information on the methods for preparing affinity adsorbents having carbohydrate ligands, and to illustrate the use of these adsorbents for the purification of representative, macromolecular substances. 

In the purification of lectins, special adsorbents have been employed. The adsorbents have been prepared by attaching specific, carbohydrate ligands to activated supports.41-106,157 An affinity adsorbent prepared from chitobiose and (2-aminoethyl)-Bio-Gel was used to purify the 2-acetamido-2-deoxy-D-glucose-binding lectin from wheat germ. The data for the purification of this lectin are shown in Fig. 6. 

Another example of the preparation of a special adsorbent is the attachment of L-fucose to agarose activated with divinyl sulfone. This affinity adsorbent was prepared, and used in the purification of two different types of lectin.20 The results on the purification of one lectin on this adsorbent are shown in Fig. 7. 

Fig. 3a. Flow diagram for the separation of the components of a complex mixture of oligosaccharides by serial lectin affinity chromatography. Depending upon the lectin adsorbant, specific oligosaccharides are either unbound (not retarded by the adsorbant), retarded (and eluted without the need of a saccharide inhibitor), or are tightly bound and then require either lOmM methyl a-D-glucopyranoside or lOOmM methyl a-D-mannopyranoside for elution. Where appropriate, each eluted peak is concentrated and the saccharide inhibitor is removed prior to application to the second affinity column. The structures of the individual oligosaccharides are shown in Fig. 3b. (Adapted from ref 288.)...

For every protein purification problem there is always an affinity solution, but cost and safety considerations may render these solutions impractical. As an example, antibodies are widely used for analysis, where only relatively small amounts are usually required, but their production and purification on a large scale for preparative-scale chromatography may be difficult to justify economically. In some cases, Hhybridoma technology may be able to address this problem. Even if production costs are acceptable, the immobilized antibodies may be unstable over the sequence of sample application, elution, and sanitation required for multiple use of the affinity adsorbent. For these reasons, while biological ligands (antibodies, enzymes, receptors, lectin. 

Palanisamy UD, Winzor DJ, Lowe CR (2000) Synthesis and evaluation of affinity adsorbents for glycoproteins an artificial lectin. J Chrom B 746 265-281... 

Kullolli M, Hancock WS, Hincapie M. Preparation of a high-performance multi-lectin affinity chromatography (HP-M-LAC) adsorbent for the analysis of human plasma glycoproteins. J Sep Sci 2008 31 2733-9. 

Polymer adsorption has also been adapted to QCM sensing whereby biofunctional thin films are adsorbed on the crystal surface with non-specific binding controlled by tuning of polymer composition. This approach proved successful as applied to carbohydrate-protein interaction by Matsuura et al. through adsorption of lactose bearing amphiphilic polymers on hydrophobic surfaces which then showed RCA12o and peanut lectin (PNA) affinity [33]. Carbohydrate surfaces prepared by photo insertion into an adsorbed polymer were tested by QCM and showed the predicted affinities [34] while in another example a covalently bound glycopolymer demonstrated Concanavalin A detection ability [35]. 

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