The reactivity of copper complexes with neuronal peptides promoted by catecholamines and its impact on neurodegeneration

In this review we give an updated outlook of the reactivity of catecholamines, particularly dopamine, and the redox effects produced by their interaction with copper(II) and dioxygen, with emphasis to the extensive studies carried out by our group. The interaction between copper(II) ions and neuronal proteins and peptides can contribute to neurodegeneration because in many cases the peptide fragments contain high affinity binding sites and the resulting complexes exhibit increased redox reactivity. It has become apparent in recent years that the redox reactivity of Cu-peptide complexes can be substantially improved by catecholamines, which are redox reactive molecules by themselves but also relatively good ligands for copper ions. Therefore, the toxic effects of copper dyshomeostasis will be particularly harmful in the brain areas producing and releasing catecholamines, i.e. the axon terminals of the substantia nigra and locus coeruleus. These are the brain regions which become affected in the early stages of Parkinson and Alzheimer's disease, indicating that copper neurotoxicity may contribute to the outset of the diseases. Copper-β-amyloid and copper-prion complexes exhibit the highest redox activity induced by catecholamines; their reactivity is modulated by interaction with membranes, which tend to depress the reactivity unless the peptides interact with each other strengthening the binding of copper(II).