Periodate Oxidation of Liposome Components

Dissolve sodium periodate to a concentration of 0.6 M by adding 128 mg per ml of water. Add 200 pi of this stock periodate solution to each ml of the liposome suspension with stirring. 

Dialyze the oxidized liposomes against 20mM sodium borate, 0.15M NaCl, pH 8.4, to remove unreacted periodate. This buffer is ideal for the subsequent coupling reaction. Chromatographic purification using a column of Sephadex G-50 also can be done. 

The periodate-oxidized liposomes may be used immediately to couple with amine-containing molecules such as proteins (see Section 7.6), or they may be stored in a lyophilized state in the presence of sorbitol (Friede et al., 1993) for latter use. 

Activation of PE Residues with Heterobifunctional Cross-linkers 

The most common type of heterobifunctional reagent used for the activation of lipid components includes the amine- and sulfhydryl-reactive cross-linkers containing an NHS ester group on one end and a maleimide, iodoacetyl, or pyridyl disulfide group on the other end (Chapter 5, Section 1). Principle reagents used to effect this activation process include SMCC (Chapter 5, Section 1.3), MBS (Chapter 5, Section 1.4), SMPB (Chapter 5, Section 1.6), SIAB (Chapter 5, Section 1.5), and SPDP (Chapter 5, Section 1.1). 

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Periodate-oxidize a liposome suspension containing glycolipid components according to Section 2 (this chapter). Adjust the concentration of total lipid to about 5mg/ml. 

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