Amphotericinb Interaction with DMPC/ERGO Mixed Lipid Bilayers

Abstract

Amphotericin B is a novel antibiotic with hydrophilic and hydrophobic ends. It can form a complex structure with sterol in the membrane. It has a good antibacterial or bactericidal effect, and it can inhibit the growth of most fungi. Although it has been used in medicine, its mechanism of action is still unclear. We used X-ray diffraction technology to measure the structure of the lipid bilayer membrane. The ergosterol and DMPC were fixed at a concentration ratio (E/L) of 1/20 and 1/40. We measured the structural changes of the lipid bilayer membrane after the addition of amphotericin B. We have found that ergosterol causes a thickening effect in DMPC and thickening as the concentration increases. However, amphotericin B causes a thinning effect in DMPC and becomes thinner as the concentration increases. The results showed that when the concentration of amphotericin B increased to A/E=1/2, the thinning effect of the two mixed lipid membranes turned into thickening. It was found that in E/L=1/20 and 1/40 mixed lipid membranes, this phenomenon occurs when the concentration of amphotericin B reaches A/L∼1/50 and 1/100. This indicates that in the two mixed lipid membranes, the concentration ratio of amphotericin B to ergosterol is higher than 1/2, and the amphotericin B and ergosterol complex will produce a state changed in the membrane. From the molecular structure model analysis, it can be inferred that this concentration has the opportunity to change the amphotericin B from the surface state to the inserted state.