The Influence of Coordination Mode on the Redox Properties of Copper Complexes with Aβ(3-16) and Its Pyroglutamate Counterpart pAβ(3-16)

Wiloch, Magdalena Z.; Baran, Natalia; Jönsson-Niedziółka, Martin

The Influence of Coordination Mode on the Redox Properties of Copper Complexes with Aβ(3-16) and Its Pyroglutamate Counterpart pAβ(3-16)

Abstract

Senile plaques are a hallmark of Alzheimer's disease. The plaques are mainly composed of small peptides from the β-amyloid (Aβ) family which differ in how they bind copper ions and thus in their properties. pAβ(3-42) species and its Aβ(3-42) precursor are found in significant proportion in the plaques; however, their complexes with copper ions are hardly explored. The electrochemical response of the copper complexes with N-truncated Aβ(3-16) and its pyroglutamate counterpart pAβ(3-16) was investigated using cyclic voltammetry. Results obtained in physiological pH (pH∼7.4) show that Cu(II) ions in these peptides undergo reduction Cu(II)/Cu(I) at a potential (Ef)∼0.05 V which in other peptides have been shown to enhance production of reactive oxygen species. Here, a voltammetric study, performed at pH below and above 7.4, reveals the effects of coordination modes on the observed redox processes. The conclusions are important for a better understanding of the pathogenesis of Alzheimer's disease.