Copper binding to the N-terminal tandem repeat region of mammalian and avian prion protein: structural studies using synthetic peptides.
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.
Hornshaw
M P
MP
MRC Neurochemical Pathology Unit, Newcastle General Hospital, Newcastle upon Tyne, United Kingdom.
McDermott
J R
JR
Candy
J M
JM
Lakey
J H
JH
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002645:Chickens; D002942:Circular Dichroism; D003300:Copper / Q000378:metabolism*; D007700:Kinetics; D008322:Mammals; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000737:chemistry*; D011328:Prions / Q000737:chemistry* / Q000378:metabolism*; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D013050:Spectrometry, Fluorescence; D013329:Structure-Activity Relationship
D010446:Peptide Fragments; D011328:Prions; D003300:Copper