title: Alzheimer's disease amyloid beta peptides in vitro electrochemical oxidation.
abstract: The oxidative behaviour of the human amyloid beta (Aβ1-40and Aβ1-42) peptides and a group of similar peptides: control inverse (Aβ40-1and Aβ42-1), mutants (Aβ1-40Phe10and Aβ1-40Nle35), rat Aβ1-40Rat, and fragments (Aβ1-28, Aβ1-16, Aβ10-20, Aβ12-28, and Aβ17-42), in solution or adsorbed, at a glassy carbon electrode, by cyclic and differential pulse voltammetry, were investigated and compared. Structurally the Aβ1-40and Aβ1-42sequences contain five electroactive amino acid residues, one tyrosine (Tyr10), three histidines (His6, His13and His14) and one methionine (Met35). The Aβ peptide 3D structure influenced the exposure of the redox residues to the electrode surface and their oxidation peak currents. Depending on the amino acid sequence length and content, the Aβ peptides gave one or two oxidation peaks. The first electron transfer reaction corresponded to the tyrosine amino acid residue oxidation, and the second to both histidines and methionine amino acid residues. The highest contribution to the second oxidation peak current was from His13, followed by His14and His6residues, and Met35residue had the lowest contribution. The Aβ peptides electron transfer depended on peptide hydrophobicity and 3D structure, the redox residues position in the sequence, the redox residues close to N-termini giving the highest oxidation peak currents.
authors.affiliation: Department of Chemistry, Faculty of Sciences and Technology, University of Coimbra, 3004-535 Coimbra, Portugal.
authors.forename: Teodor Adrian
authors.initials: TA
authors.lastname: Enache
authors.affiliation: Department of Chemistry, Faculty of Sciences and Technology, University of Coimbra, 3004-535 Coimbra, Portugal. Electronic address: brett@ci.uc.pt.
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Oliveira-Brett
mesh_terms: D016229:Amyloid beta-Peptides / Q000737:chemistry*; D004563:Electrochemistry; D004579:Electron Transport; D006801:Humans; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D008958:Models, Molecular; D010446:Peptide Fragments / Q000737:chemistry*; D066329:Protein Aggregates; D017433:Protein Structure, Secondary
chemical_list: D016229:Amyloid beta-Peptides; D010446:Peptide Fragments; D066329:Protein Aggregates; C078592:amyloid beta-protein (1-40); C075222:amyloid beta-protein (1-42)
keywords: Adsorption; Alzheimer's disease; Amyloid beta peptide oxidation; Electroactive amino acids; Glassy carbon electrode; Voltammetry