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Updated: Jan 2, 2026
Quantifying the Binding Interactions Between CuII and Peptide Residues in the Presence and Absence of Chromophores
Published on: April 5, 2022
Coordination sphere tuning of the electron transfer dissociation behavior of Cu(II)-peptide complexes
1Department of Chemistry, University of Massachusetts, LGRT 701, 10 N. Pleasant St., Amherst, MA 01003, USA.
Abstract:
In contrast to previous electron capture dissociation (ECD) studies, we find that electron transfer dissociation (ETD) of Cu(II)-peptide complexes can generate c- and z-type product ions when the peptide has a sufficient number of strongly coordinating residues. Double-resonance experiments, ion-molecule reactions, and collision-induced dissociation (CID) prove that the c and z product ions are formed via typical radical pathways without the associated reduction of Cu(II), despite the high second ionization energy of Cu. A positive correlation between the number of Cu(II) binding groups in the peptide sequence and the extent of c and z ion formation was also observed. This trend is rationalized by considering that the recombination energy of Cu(II) can be lowered by strong binding ligands to an extent that enables electron transfer to non-Cu sites (e.g., protonation sites) to compete with Cu(II) reduction, thereby generating c/z ions in a manner similar to that observed for protonated (i.e., nonmetalated) peptides.
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