Micelle-like architecture of monomeric amyloid beta peptide

The movie shows conformational fluctuations (via Monte Carlo sampling) at equilibrium of the monomeric Alzheimer's Aβ1-40 peptide at 280K (data are from only a single replica-exchange Monte Carlo simulation spanning four temperatures in the physiological range). Displayed in blue CPK representation are positively charged sidechains, in red CPK representation negatively charged sidechains except E22 and D23 which are displayed in red licorice representation. The polypeptide backbone is shown in Cartoon representation and the surface of all hydrophobic residues in transparent surface representation. The movie shows how a fluid hydrophobic core is maintained throughout (although it occasionally ruptures) with the peptide being overall collapsed and "decorated" by charged sidechains. This resembles features of a canonical micelle only for a monomeric polymer. Fluctuations are large in particular at the N-terminus (left side of screen). The sidechains of E22 and D23 are often involved in a tight turn, occasionally "nucleating" a β-hairpin in this particular simulation. Secondary structure formation is transient and occurs more often in the central part of the peptide.