title: Hydrogen exchange-mass spectrometry analysis of beta-amyloid peptide structure.
abstract: beta-Amyloid peptide (A beta) is the primary protein component of senile plaques in Alzheimer's disease and is believed to be responsible for the neurodegeneration associated with the disease. A beta has proven to be toxic only when aggregated; however, the structure of the aggregated species associated with toxicity is unknown. In the present study, we use hydrogen-deuterium isotope exchange (HX)-electrospray ionization mass spectrometry (MS) along with enzymatic digestion as a tool to examine at near residue level, the changes in A beta structure associated with aggregation to a fibril form. Our results show that the structure of A beta intermediate species formed early in the course of fibrillogenesis is dependent upon solvent conditions. Additionally, the HX-MS data of peptic A beta fragments suggest that the C-terminal segment of the peptide is approximately 35% protected from exchange in fibril-containing samples, relative to monomeric A beta species prepared in DMSO/H(2)O. The N-terminus (residues 1-4) is completely unprotected from exchange, and the fragment containing residues 5-19 is over 50% protected from exchange in the fibril-containing samples. This work contributes to our understanding of A beta structure associated with aggregation and toxicity and further application of this approach may aid in the design of agents that intervene in the A beta aggregation processes associated with neurotoxicity.
authors.affiliation: Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843-3122, USA.
authors.forename: Steven S-S
authors.initials: SS
authors.lastname: Wang
authors.forename: Scott A
authors.initials: SA
authors.lastname: Tobler
authors.forename: Theresa A
authors.initials: TA
authors.lastname: Good
authors.forename: Erik J
authors.initials: EJ
authors.lastname: Fernandez
mesh_terms: D016229:Amyloid beta-Peptides / Q000737:chemistry* / Q000648:ultrastructure; D052160:Benzothiazoles; D003224:Congo Red; D005453:Fluorescence; D006801:Humans; D006859:Hydrogen; D057927:Hydrophobic and Hydrophilic Interactions; D010446:Peptide Fragments / Q000737:chemistry* / Q000648:ultrastructure; D017434:Protein Structure, Tertiary; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013844:Thiazoles / Q000737:chemistry
chemical_list: D016229:Amyloid beta-Peptides; D052160:Benzothiazoles; D010446:Peptide Fragments; D013844:Thiazoles; C078592:amyloid beta-protein (1-40); C009462:thioflavin T; D003224:Congo Red; D006859:Hydrogen