Figure 2.

Effects of cobra cardiotoxins CTII and CTI on the ³¹P NMR-spectra of large unilamellar liposomes. ³¹P-NMR spectra of multilamellar liposomes of pure phosphatidylcholine (PC) (lower spectra), PC + 0.25% cardiolipin (CL) (middle spectra) and PC + 0.5% CL (upper spectra) containing a total phospholipid concentration of 6.4 × 10⁻² M and treated with 8 × 10⁻⁴ M CTII. ³¹P-NMR spectra were recorded at 18 °C. The percentage of non-bilayer immobilized phospholipids was estimated by calculating the area under the signal B at 4.9 ppm remained after a DANTE train of saturation was applied at the high-field peak S of the lamellar spectrum (saturated spectra not shown). The percentages of non-bilayer immobilized phospholipids are shown on the column on the left as means with standard errors (± SEM) compiled from three independent experiments. Statistical differences were observed between the pure PC liposomes vs. liposomes with 2.5% CL or 5% CL (one-way ANOVA, Fisher’s LSD). Each ³¹P-NMR spectrum shown is representative of two independent experiments that showed similar results. Each sample was measured in triplicate readings.