Evaluation of copper2+ affinities for the prion protein.

The prion protein (PrP) is a cell-surface Cu2+ binding glycoprotein which can bind six copper ions. The role of Cu2+ in PrP function, misfolding, and prion disease has generated much interest; however, the field has been hampered by a lack of consensus with regard to the affinity of Cu2+ for PrPC. Here we build on our understanding of the appearance of visible CD spectra for full-length PrP and fragments to determine the affinity of Cu2+ for four different binding modes, with dissociation constants ranging between 13 and 66 nM at pH 7.4.