Fig. 2.
Modeling the binding of PFO to DOPC membranes. The procedure was as described for Fig. 1. The symbols depict experimental data from two studies (41, 45). Curves were calculated using the values in Table 2. A literature value for the sterol-phospholipid affinity constant, KP = 930, was assumed (8). The stoichiometric equivalence point for C:P = 1:2 is C/P = 0.5 mol/mol or 33 mol %; that for a membrane containing equal proportions of C:P = 1:1 and C:P = 1:2 is C/P = 0.75 mol/mole or 43 mol %. For reference, curve 5 shows uncomplexed cholesterol in the absence of a ligand, assuming C:P = 1:2, and curve 6 shows uncomplexed cholesterol in the absence of a ligand assuming an equimolar mixture of C:P = 1:1 and C:P = 1:2. DOPC, 1,2-dioleoyl-sn-glycero-3-phosphocholine; PFO, perfringolysin O.