Use of Glycolipids and Lectins to Effect Specific Conjugations

2mg/ml in water. Since an aqueous solution of the crosslinker will degrade by hydrolysis of the sulfo-NHS ester, it should be used quickly to prevent significant loss of activity. If a sufficiently large amount of liposomes will be modified, the solid sulfo-LC-SPDP may be added directly to the reaction mixture without preparing a stock solution in water. 

Add 25-50 pi of the stock solution of either SPDP or LC-SPDP in DMF to each ml of the liposome suspension to be modified. If sulfo-LC-SPDP is used, add 50-100 pi of the stock solution in water to each ml of liposome suspension. 

Mix and react for at least 30 minutes at room temperature. Longer reaction times, even overnight, will not adversely affect the modification. 

Purify the modified liposomes from reaction by-products by dialysis or gel filtration using a column of Sephadex G-50. 

The SPDP-activated liposomes may be used immediately to couple with sulfhydryl-containing molecules such as proteins (see Section 7.7, this chapter), or they may be stored in a lyophilized state in the presence of sorbitol (Friede et al., 1993) for latter use. 

Hgure 344 Glycolipid components included in liposome consttuction may be used to couple antibody molecules by using conjugates of lectins with the proper specificity for binding the sugar groups. 

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