Abstract
The interaction between lipid bilayers and Amyloid β peptide (Aβ) plays a critical role in proliferation of Alzheimer’s disease (AD). AD is expected to affect one in every 85 humans by 2050 and therefore deciphering the interplay of Aβ and lipid bilayers in the molecular level is of profound importance. In this work, we have studied Aβ(1-40) in the presence of dimyristoyl-glycero-phosphoglycerol (DMPG) bilayers. The conformational transitions of Aβ in the presence of DMPG were studied by circular dichroism, oriented circular dichroism, Fourier transform infrared spectroscopy and fluorescence spectrofluorometry. These results are substantiated with structural investigations of DMPG bilayers using dynamic light scattering, Small Angle Neutron Scattering, and Neutron Membrane Diffraction. To understand the effect of Aβ on the dynamics of DMPG molecules, high resolution Quasi-Elastic Neutron Scattering experiments were carried out on DMPG vesicles in both solid gel and fluid phase. It is found that addition of Aβ affects mainly the slower lateral motion of lipid molecules especially in the fluid phase but not internal motions. Our investigations reveal that Aβ anchors firmly to the highly charged DMPG bilayers around headgroup region, and it doesn’t penetrate deeply into the bilayer.
