Secondary Structure and Interfacial Aggregation of Amyloid-β(1−40) on Sodium Dodecyl Sulfate Micelles†

Alzheimer's disease (AD) is characterized by the presence of large numbers of fibrillar amyloid deposits in the form of senile plaques in the brain. The fibrils in senile plaques are composed of 40- and 42-residue amyloid-β (Aβ) peptides. Several lines of evidence indicate that fibrillar Aβ and especially soluble Aβ aggregates are important in the pathogenesis of AD, and many laboratories have investigated soluble Aβ aggregates generated from monomeric Aβ in vitro. Of these in vitro aggregates, the best characterized are called protofibrils. They are composed of globules and short rods, show primarily β-structure by circular dichroism (CD), enhance the fluorescence of bound thioflavin T, and readily seed the growth of long fibrils. However, one difficulty in correlating soluble Aβ aggregates formed in vitro with those in vivo is the high probability that cellular interfaces affect the aggregation rates and even the aggregate structures. Reports that focus on the features of interfaces that are important i...