Effect of Zn²⁺ ions on the assembly of amylin oligomers: Insight into the molecular mechanisms

Amylin is an endocrine hormone and is a member of the family of amyloid peptides and proteins that emerge as potential scaffolds by self-assembly processes. Zn²⁺ ions can bind to amylin peptides to form self-assembled Zn²⁺-amylin oligomers. In the current work the binding sites of Zn²⁺ ions in the self-assembled amylin oligomers at various concentrations of zinc have been investigated. Our results yield two conclusions. First, in the absence of Zn²⁺ ions polymorphic states (i.e. various classes of amylin oligomers) are obtained, but when Zn²⁺ ions bind to amylin peptides to form Zn²⁺-amylin oligomers, the polymorphism is decreased, i.e. Zn²⁺ ions bind only to specific classes of amylin. At low concentrations of Zn²⁺ ions the polymorphism is smaller than at high concentrations. Second, the structural features of the self-assembled amylin oligomers are not affected by the presence of Zn²⁺ ions. This study proposes new molecular mechanisms of the self-assembly of Zn²⁺-amylin oligomers.