A peptide fragment of human prion protein, HuPrP(106–126), has been reported to mimic the pathological features underlying prion diseases. Although the actual neurotoxic mechanism of HuPrP(106–126) has not been elucidated, several hypotheses has been proposed based on the role for copper. In this study, to understand the toxic function of HuPrP(106–126) from a viewpoint of electrochemical competence, we investigated redox properties of copper ion complexes with four different binding motifs of a model of HuPrP(106–126) based on density functional theory calculations. We found that the HuPrP(106–126)-derived models exhibited diverse redox activities that depended on copper-binding conformations.