Affinity partitioning of biotinylated mixed liposomes: Effect of charge on biotin-NeutrAvidin interaction

Irene Barinaga-Rementeria Ramírez, Lars Ekblad, Bengt Jergil

    Research output: Contribution to journalArticlepeer-review


    The partitioning behaviour of biotinylated mixed liposomes in aqueous poly(ethylene glycol)/dextran two-phase systems containing NeutrAvidin- dextran suggests that the biotin-NeutrAvidin affinity interaction is charge dependent. Biotinylated phosphatidylcholine liposomes with a low negative surface charge distributed in the NeutrAvidin-containing bottom phase at neutral pH, but the introduction of additional negative charges by including phosphatidylserine or the surfactant sodium dodecylsulfate in the liposomes caused them to distribute in the poly(ethylene glycol)-rich top phase instead. By gradually lowering the pH of the affinity two-phase system below the isoelectric point (6.3) of NeutrAvidin, negatively charged phosphatidylserine/phosphatidylcholine liposomes increasingly were attracted by NeutrAvidin to the bottom phase. It is suggested that acidic amino acids present at the rim of the biotin-binding pocket of NeutrAvidin may interact electrostatically with charged residues of the closely apposed liposome surface affecting the affinity interaction. (C) 2000 Elsevier Science B.V.
    Original languageEnglish
    Pages (from-to)389-396
    Number of pages7
    JournalJournal of Chromatography B: Biomedical Sciences and Applications
    Issue number1-2
    Publication statusPublished - 23 Jun 2000


    • Aqueous two-phase systems
    • Biotin
    • Liposomes
    • NeutrAvidin
    • Partitioning
    • Phospholipids


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