Simulation study of the structure and dynamics of the Alzheimer's amyloid peptide congener in solution

The amyloid A beta (10-35)-NH(2) peptide is simulated in an aqueous environment on the nanosecond time scale. One focus of the study is on the validation of the computational model through a direct comparison of simulated statistical averages with experimental observations of the peptide's structure and dynamics. These measures include (1) nuclear magnetic resonance spectroscopy-derived amide bond order parameters and temperature-dependent H(alpha), proton chemical shifts, (2) the peptide's radius of gyration and end-to-end distance, (3) the rates of peptide self-diffusion in water, and (4) the peptide's hydrodynamic radius as measured by quasielastic light scattering experiments. A second focus of the study is the identification of key intrapeptide interactions that stabilize the central structural motif of the peptide. Particular attention is paid to the structure acid fluctuation of the central LVFFA hydrophobic cluster (17-21) region and the VGSN turn (24-27) region. There is a strong correlation between preservation of the structure of these elements and interactions between the cluster and turn regions in imposing structure on the peptide monomer. The specific role of these interactions in relation to proposed mechanisms of amyloidosis is discussed.