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Updated: Apr 27, 2026

Quantifying the Binding Interactions Between CuII and Peptide Residues in the Presence and Absence of Chromophores
Published on: April 5, 2022
The Cu²⁺ binding properties of branched peptides based on L-2,3-diaminopropionic acid
Łukasz Szyrwiel1, Łukasz Szczukowski, József S Pap
1CNRS/UPPA, LCABIE, UMR5254 , Hélioparc, 2, av. Pr. Angot, F-64053 Pau, France.
Abstract:
Three new branched peptides, namely, H-Gly-Dap(H-Gly)-Gly-NH2 (3G), H-His-Dap(H-His)-Gly-NH2 (2HG), and H-Gly-Dap(H-Gly)-His-NH2 (2GH), where Dap stands for the 2,3-diaminopropionic acid residue, were synthesized by solid phase procedures. Because of the junction at Dap these peptides have three available pending arms for metal chelation. The complex formation between these peptides and 1 equiv of Cu(2+) was investigated as a function of pH by potentiometry ultraviolet-visible absorption, circular dichroism, and X-band electron paramagnetic resonance spectroscopy in aqueous medium. Our results clearly demonstrate that cooperation between all three peptide arms essentially contributes to the stability of copper(II) complexes.
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Structures of Carboxylic Acid Derivatives
Carboxylic acid derivatives contain an acyl group attached to a heteroatom such as chlorine, oxygen, or nitrogen. The carbonyl carbon and oxygen are both sp2-hybridized with an unhybridized p orbital.
The three sp2 orbitals of the carbonyl carbon form three σ bonds, one each with the carbonyl oxygen, the α carbon, and the heteroatom, whereas the other two sp2 orbitals of the carbonyl oxygen are occupied by the lone pairs. Further, the...

