Investigating structural details of lipid-cholesterol-A$\beta $ interactions

Alzheimer's disease (AD) is the most common form of dementia and is predicted to affect 1 in 85 people around the world by 2050. Amyloid beta (A$\beta )$-peptide, a peptide composed of 40- 42 amino acids that is the product of cleavage from the amyloid precursor protein (APP), is regarded to play a major role in the development of AD. In addition, accumulating evidence points to a positive association between cholesterol and AD. Here, we present results from our studies about A$\beta $-peptide and cholesterol in bilayer by small-angle neutron scattering (SANS) using a combination of dimyristoyl, phosphocholine (DMPC) and partially deuterated cholesterol (cholesterol-d7) with and without A$\beta $. We compare the results using grazing incidence and transmission SANS on lipid bilayer films and unilamellar vesicles respectively. The structural details on vesicles and bilayers work in conjunction with the circular dichroism on peptide in solution and oriented circular dichroism in bilayer films. The studies confirm a positive association of A$\beta $ with the membrane layers. The results from different studies will be compared and contrasted in presentation.