title: Conformational-Sensitive Fast Photochemical Oxidation of Proteins and Mass Spectrometry Characterize Amyloid Beta 1-42 Aggregation.
abstract: Preventing and treating Alzheimer's disease require understanding the aggregation of amyloid beta 1-42 (Aβ1-42) to give oligomers, protofibrils, and fibrils. Here we describe footprinting of Aβ1-42 by hydroxyl radical-based fast photochemical oxidation of proteins (FPOP) and mass spectrometry (MS) to monitor the time-course of Aβ1-42 aggregation. We resolved five distinct stages characterized by two sigmoidal behaviors, showing the time-dependent transitions of monomers-paranuclei-protofibrils-fibrillar aggregates. Kinetic modeling allows deciphering the amounts and interconversion of the dominant Aβ1-42 species. Moreover, the irreversible footprinting probe provides insights into the kinetics of oligomerization and subsequent fibrillar growth by allowing the conformational changes of Aβ1-42 at subregional and even amino-acid-residue levels to be revealed. The middle domain of Aβ1-42 plays a major role in aggregation, whereas the N-terminus retains most of its solvent-accessibility during aggregation, and the hydrophobic C-terminus is involved to an intermediate extent. This approach affords an in situ, real-time monitoring of the solvent accessibility of Aβ1-42 at various stages of oligomerization, and provides new insights on site-specific aggregation of Aβ1-42 for a sample state beyond the capabilities of most other biophysical methods.
authors: Department of Chemistry, Washington University in St. Louis , St. Louis, Missouri 63130, United States.
authors: Ke Sherry
authors: KS
authors: Li
authors: Department of Chemistry, Washington University in St. Louis , St. Louis, Missouri 63130, United States.
authors: Don L
authors: DL
authors: Rempel
authors: Department of Chemistry, Washington University in St. Louis , St. Louis, Missouri 63130, United States.
authors: Michael L
authors: ML
authors: Gross
mesh_terms: D016229:Amyloid beta-Peptides / Q000737:chemistry*; D055592:Biophysical Phenomena; D013058:Mass Spectrometry; D008958:Models, Molecular; D010084:Oxidation-Reduction; D055668:Photochemical Processes; D066263:Protein Aggregation, Pathological; D011487:Protein Conformation
chemical_list: D016229:Amyloid beta-Peptides