The structural change from PrP
C to PrP
Sc of the prion protein is thought to relate to Cu
2+ binding to the His residue. In this study, the binding abilities of 9 synthetic fragment peptides of human PrP
C, 4 peptides containing 1 to 4 OP-repeat (OP-1 to OP-4) and 5 peptides including the His residue, to various metal ions was tested by a column-switch HPLC composed of a chelating column and a reverse-phase column. OP-4 binds to the Cu
2+ chelating column, but not to the Mn
2+ chelating column. These binding abilities are the same as results obtained by CD analysis. Interestingly, all peptides tested here except for OP-1 bound to a Cu
2+ chelating column. In addition, OP-repeat also bound to Ni
2+, Zn
2+ and Co
2+, but almost all other peptides did not bind to those metal ions. These results strongly support that the column switch HPLC used here is a conventional method to analyze the binding affinity of peptides to various metal ions. The results obtained here suggest that Cu
2+ binding to His residues outside of OP-repeat participate in structural changing from PrP
C to PrP
Sc.
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