Title:Electrochemistry of Alzheimer Disease Amyloid Beta Peptides
Volume: 25
Issue: 33
Author(s): Ana-Maria Chiorcea-Paquim, Teodor Adrian Enache and Ana Maria Oliveira-Brett*
Affiliation:
- Department of Chemistry, Faculty of Sciences and Technology, University of Coimbra, 3004-535, Coimbra,Portugal
Keywords:
Alzheimer's disease (AD), amyloid beta (Aβ) peptide, voltammetry, fibrilization, aggregation,
adsorption, oxidation, AD biomarkers.
Abstract: Alzheimer’s disease (AD) is a widespread form of dementia that is estimated to
affect 44.4 million people worldwide. AD pathology is closely related to the accumulation of
amyloid beta (Aβ) peptides in fibrils and plagues, the small oligomeric intermediate species
formed during the Aβ peptides aggregation presenting the highest neurotoxicity.
This review discusses the recent advances on the Aβ peptides electrochemical
characterization. The Aβ peptides oxidation at a glassy carbon electrode occurs in one or two
steps, depending on the amino acid sequence, length and content. The first electron transfer
reaction corresponds to the tyrosine Tyr10 amino acid residue oxidation, and the second to all
three histidine (His6, His13 and His14) and one methionine (Met35) amino acid residues. The
Aβ peptides aggregation and amyloid fibril formation are electrochemically detected via the
electroactive amino acids oxidation peak currents decrease that occurs in a time dependent
manner. The Aβ peptides redox behaviour is correlated with changes in the adsorption
morphology from initially random coiled structures, corresponding to the Aβ peptide
monomers in random coil or in α-helix conformations, to aggregates, protofibrils and two
types of fibrils, corresponding to the Aβ peptides in a β-sheet configuration, observed by
atomic force microscopy. Electrochemical studies of Aβ peptides aggregation, mediated by
the interaction with metal ions, particularly zinc, copper and iron, and different methodologies
concerning the detection of Aβ peptide biomarkers of AD in biological fluids, using
electrochemical biosensors, are also discussed.
