Towards High-Throughput Modelling of Copper Reactivity Induced by Structural Disorder in Amyloid Peptides

Abstract

Transition metal ions often interact with disordered proteins. The affinity is high enough to compete with structured proteins, but the catalytic activity of the metal centre is often out of control and, therefore, potentially dangerous for cells. An example is a single copper ion interacting with the amyloid-β (Aβ) peptide and triplet dioxygen, an interaction that is fundamental in producing reactive oxygen species in neurodegeneration. High-throughput modelling of the Cu-Aβ-O2 system was performed with the aim of providing a tool to dissect the structural features that characterise dangerous Cu-based catalysts in neurodegeneration. This study showed that the production of superoxide is a process with low-energy intermediate species, once a small population of high-energy CuI-Aβ complex is formed. This population is enhanced when Cu bridges two different peptides in 1:1 Cu:Aβ dimers. Despite the bias for high-energy reduced reactant species, the reduction of CuII-Aβ product by superoxide can also occur, in addition to that by ascorbate, because the structural disorder produces a small population of oxidant species characterised by unstable CuII coordination, coexisting with the most abundant reductant species, characterised by stable CuII coordination.