Electrochemical and optical study of metallothionein interactions with prion proteins

The prion protein (PrP^C) can be structurally shifted to its PrP^Sc isoform causing a wide range of neurodegenerative diseases, which are currently incurable. There is an evidence that metallothioneins (MTs), and especially MT-3, are associated with neurodegenerative diseases. PrP^C and MTs play pivotal roles in maintaining metal homeostasis; therefore, it is conceivable that each of them has its own significance in prion diseases. In this paper, we study the nature of interactions between PrP^C, MT, and copper ions, Cu(II), using the method of differential pulse voltammetry (DPV) coupled with adsorptive transfer stripping technique (AdTS). Electrochemical properties of PrP itself and its interactions with both the Cu(II) ions and MTs have been found. Based on the results obtained, we hypothesised the formation of the complex in molar ratio 2:1 (PrP^C:MT). Surface plasmon resonance imaging (SPRi) was used as a control reference assay to further confirm results obtained by the electrochemical approach, such as the specific interactions between PrP^C and MT-3.