Chemical and Pharmaceutical Bulletin
Online ISSN : 1347-5223
Print ISSN : 0009-2363
ISSN-L : 0009-2363
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Metal-Binding Ability of Human Prion Protein Fragment Peptides Analyzed by Column Switch HPLC
Aya KojimaYasunori MabuchiMotomi KonishiRika OkiharaMakoto NaganoToshifumi Akizawa
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2011 Volume 59 Issue 8 Pages 965-971

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Abstract

The structural conversion of the prion protein (PrP) from the normal cellular isoform (PrPC) to the posttranslationally modified form (PrPSc) is thought to relate to Cu2+ binding to histidine (H) residues. Traditionally, the binding of metals to PrP has been investigated by monitoring the conformational conversion using circular dichroism (CD). In this study, the metal-binding ability of 21 synthetic peptides representing regions of human PrPC was investigated by column switch high-performance liquid chromatography (CS-HPLC). The CS-HPLC system is composed of a metal chelate affinity column and an octadecylsilica (ODS) reversed-phase column that together enable the identification of metal-binding regardless of conformational conversion. Synthetic peptides were designed with respect to the position of H residues as well as the secondary structure of human PrP (hPrP). The ability of the octapeptide (PHGGGWGQ)-repeating region (OP-repeat) to bind metals was analyzed by CS-HPLC and supported by CD analysis, and indicated that CS-HPLC is a reliable and useful method for measuring peptide metal-binding. Peptides from the middle region of hPrP showed a high affinity for Cu2+, but binding to Zn2+, Ni2+, and Co2+ was dependent on peptide length. C-Terminal peptides had a lower affinity for Cu2+, Zn2+, Ni2+, and Co2+ than OP-repeat region peptides. Interestingly, hPrP193—230, which contained no H residues, also bound to Cu2+, Zn2+, Ni2+, and Co2+, indicating that this region is a novel metal-binding site in the C-terminal region of PrPC. The CS-HPLC method described in this study is useful and convenient for assessing metal-binding affinity and characterizing metal-binding peptides or proteins.

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© 2011 The Pharmaceutical Society of Japan
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