Abstract
Isothermal titration calorimetry (ITC) was used to study the interactions between copper(II) ions and peptides with sequences taken from the N-terminal loop of the FBP28 protein (formin-binding protein) WW domain: Ac-Lys-Thr-Ala-Asp-Gly-Lys-Thr-NH2 (D7) and Ac-Tyr-Lys-Thr-Ala-Asn-Gly-Lys-Thr-Tyr-NH2 (D9 M), respectively. Measurements were taken at 298.15 K in 20 mM 2-(N-morpholino)ethanesulfonic acid buffer solution at a pH of 6. The stoichiometry, conditional stability constants and thermodynamic parameters (ΔITCG, ΔITCH and ΔITCS) for the pertinent complexation reactions were determined. Furthermore, the thermal stability of peptide conformations in the presence and absence of copper(II) in the system was investigated using differential scanning calorimetry. Finally, a general procedure on how to include the effect of buffer competition with the peptide for the metal as well as proton competition with the metal for the peptide and the buffer’s component during ITC data analysis is described.
Highlights
Peptides have been known to act as chelating agents
Isothermal titration calorimetry (ITC) was used to study the interactions between copper(II) ions and peptides with sequences taken from the N-terminal loop of the FBP28 protein WW domain: AcLys-Thr-Ala-Asp-Gly-Lys-Thr-NH2 (D7) and Ac-Tyr-LysThr-Ala-Asn-Gly-Lys-Thr-Tyr-NH2 (D9 M), respectively
We present the affinities of two peptides derived from the N-terminal part of the FBP28 protein (PDB code: 1E0L) to copper (Cu2?)
Summary
Peptides have been known to act as chelating agents. Their complex-forming capacity has been utilized in medicine for the treatment of Wilson’s disease, for the removal of excess of copper from the liver, and in the prevention of itsThe b-hairpin from the FBP28 protein is known to initiate the folding of this protein [8]. Peptides have been known to act as chelating agents. Their complex-forming capacity has been utilized in medicine for the treatment of Wilson’s disease, for the removal of excess of copper from the liver, and in the prevention of its. The b-hairpin from the FBP28 protein is known to initiate the folding of this protein [8]. This is an independently forming region whose folding is not induced by a b-hairpin and is an excellent object by which to study the factors that influence b-hairpin formation. Ion, a longer (9 residues) peptide fragment from FBP28 (1E0L 11–19) was selected. The effect of elongating the peptide chain with side chains that bear expanded side chains (tyrosines) on the binding properties of the D7 peptide was investigated
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