The recombinant protein annexin V, isolated from bacteria Escherichia coli BL21(DE3)
cells, shows a strong affinity for lipid membranes supplemented with phosphatidylserine
or cardiolipin. Phosphatidylserine, which is typically present in the inner layer of the
plasma membrane, and cardiolipin, which is naturally present mostly in the inner
mitochondrial membrane, are externalized to the plasmalemma surface during the
process of apoptosis. Fluorescently labelled annexin V (annexin V-FITC) was shown to
interact with phosphatidylserine and is widely used as a molecular probe for the
detection of apoptotic cells. In this MSc thesis, we analyzed the interactions of
recombinant proteins annexin V, fluorescently labeled annexin V-FITC, and EryA
mCherry with lipid vesicles of different compositions using surface plasmon resonance
technique. We confirmed that calcium ions are important for the binding of the tested
proteins to lipid vesicles. Our results indicate that recombinant annexin V does not bind
specifically to the apoptotic lipid markers phosphatidylserine and cardiolipin but rather
interacts with all negatively charged membrane glycerophospholipids. Similarly,
annexin V-FITC interacts strongly and non-specifically with negatively charged
glycerophospholipids, while EryA-mCherry moderately binds to cardiolipin, and shows
a high binding affinity for the membrane sphingolipid ceramide phosphoethanolamine.
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