Figure 4.

Membrane fragmentation through a detergent-like mechanism induced by hIAPP fibers. Lipid concentration in the supernatant after incubation with 15 μM hIAPP for 24 hr at 25°C with 1 mg/ml LUVs of POPC/POPS (molar ratio 7:3) in the presence or absence of 100 μM Ca²⁺, and centrifugation at 14,000 rpm as measured by the Stewart assay. Black bars represent controls in the absence of peptide. The presence of Ca²⁺ significantly enhances fragmentation of membranes induced by hIAPP fiber formation. All experiments were performed in 10 mM HEPES buffer, 100 mM NaCl, pH 7.4 at 25°C. Results are the average of three experiments. The error bars indicate the standard error of measurement.