NR AXFX
AU Shields,S.B.; Franklin,S.J.
TI Investigation of the affinity and selectivity of avian prion hexarepeat peptides for physiological divalent metal ions
QU Journal of Inorganic Biochemistry 2007 May; 101(5): 783-8
PT journal article; research support, non-u.s. gov't
AB To further the understanding of the biological importance of metal-binding by avian prion proteins, we have investigated the affinity and selectivity of peptides Hx1 [Ac-HNPGYP-nh] and Hx2 [Ac-NPGYPHNPGYPH-nh] with a range of physiological metals via electrospray ionization mass spectrometry and tyrosine fluorescence emission spectroscopy. Both the hexamer Hx1 and the "dimer" peptide Hx2 bind only one equivalent of Cu(II), although only the latter peptide binds copper with significant affinity (Hx1 K(d)=150+/-35 microM; Hx2 K(d)=1.07+/-0.78 microM, pH 7.0 in 3-(N-morpholino)propanesulfonic acid (MOPS) buffer). Both peptides are selective for Cu(II) over divalent Ca, Co, Mg, Mn, Ni, and Zn. Cyclic voltammetry was used to estimate Cu(II/I) solution potentials at pH 6.8, which were very similar for the two peptides (CuHx1 E degrees'=+350 mV, CuHx2 E degrees'=+320 mV vs. normal hydrogen electrode). These results suggest similar binding modes for the two peptides, and relative stabilization of Cu(I) relative to similar His-Gly-rich peptides in the literature.
MH Animals; Cations, Divalent/metabolism; Chickens; Copper/*metabolism; Prions/*metabolism; Protein Binding; Spectrometry, Fluorescence; Spectrometry, Mass, Electrospray Ionization; Substrate Specificity; Tyrosine/metabolism
AD Department of Chemistry, University of Iowa, Iowa City, IA 52242, USA.
SP englisch
PO USA