Coordinative unsaturated CuI entities are crucial intermediates governing cell internalization of copper. A combined experimental ESI-MS and DFT study.

Model peptides relevant to hCtr1 transchelate CuI from the antitumour [CuI(PTA)4]+ complex before metal internalization into tumor cells. ESI(+)MS experiments corroborated by DFT calculations indicate that tetracoordinated-CuII and linear-CuI arrangements of in-situ generated copper-peptide products play a crucial role in promoting the transfer of copper from the terminal MDH portion into adjacent HSH peptide sequence.