Copper Binding to the N-terminal Tandem Repeat Region of Mammalian and Avian Prion Protein: Structural Studies Using Synthetic Peptides

Biochem Biophys Res Commun. 1995 Sep 25;214(3):993-9. doi: 10.1006/bbrc.1995.2384.

Abstract

Using CD spectroscopy we have investigated the effect of Cu2+ on the secondary structure of synthetic peptides Octa4 and Hexa4 corresponding to tetra-repeats of the octapeptide of mammalian PrP and the hexapeptide of chicken PrP. In addition, fluorescence spectroscopy was used to estimate the dissociation constants (Kd), of Cu2+ binding by both peptides. Both peptides exhibited unusual CD spectra, complicated by the high proportion of aromatic residues, revealing little secondary structure in aqueous solution. Addition of Cu2+ to Hexa4 induced an increase in random coil to resemble Octa4. The fluorescence of both peptides was quenched by Cu2+ and this was used to calculate Kd's of 6.7 microM for Octa4 and 4.5 microM for Hexa4. Other divalent cations showed lesser effects on the fluorescence of the peptides.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Binding Sites
  • Chickens
  • Circular Dichroism
  • Copper / metabolism*
  • Kinetics
  • Mammals
  • Molecular Sequence Data
  • Peptide Fragments / chemical synthesis
  • Peptide Fragments / chemistry*
  • Prions / chemistry*
  • Prions / metabolism*
  • Protein Conformation*
  • Protein Structure, Secondary*
  • Spectrometry, Fluorescence
  • Structure-Activity Relationship

Substances

  • Peptide Fragments
  • Prions
  • Copper