Kinetic Defects Induced by Melittin in Model Lipid Membranes: A Solution Atomic Force Microscopy Study.

摘要: Quantitative characterization of membrane defects (pores) is important for elucidating the molecular basis many membrane-active peptides. We study kinetic induced by melittin in vesicular and planar lipid bilayers. Fluorescence spectroscopy measurements indicate that induces time-dependent calcein leakage. Solution atomic force microscopy (AFM) used to visualize melittin-induced defects. After initial equilibration, most probable defect radius ∼3.8 nm 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) Unexpectedly, become larger with longer incubation, accompanied substantial shape transformation. The ∼4.7 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) Addition 30 mol % cholesterol DOPC bilayers suppresses kinetics, although inhibitory impact negated incubation. Overall, rate development follows DLPC > DOPC/cholesterol. Kinetic are also observed when anionic lipids present. Based on observation can occupy as large 40% bilayer surface, we propose a growth model. effect phase behavior DOPC/egg-sphingomyelin/cholesterol find initially or eliminates liquid-ordered (Lo) domains; Lo domains gradually emerge dominant species incubation; phase-coexisting have ∼5 exclusively localized liquid-disordered (Ld) phase. Our experimental data highlight not static; conversely, spontaneous intrinsically associated permeabilization exerted melittin.