Key Intermediate Species Reveal the Copper(II)‐Exchange Pathway in Biorelevant ATCUN/NTS Complexes

• DOI: 10.1002/anie.202004264
• Publication Date: 2020-04-08T12:22:40Z
• Authors: Radosław Kotuniak; Marc J. F. Stramp...; Karolina Bossak‐A...; Urszula E. Wawrzy...; Iwona Ufnalska; Peter‐Leon Hagedoorn; Wojciech Bal
• Keywords: Ion Transport; amino-terminal copper and nickel (ATCUN) motif; Proteins; Surface Plasmon Resonance; 01 natural sciences; 333; Communications; 0104 chemical sciences; electrochemistry; copper; peptides; Spectrophotometry, Ultraviolet; Copper; EPR spectroscopy

AbstractThe amino‐terminal copper and nickel/N‐terminal site (ATCUN/NTS) present in proteins and bioactive peptides exhibits high affinity towards CuII ions and have been implicated in human copper physiology. Little is known, however, about the rate and exact mechanism of formation of such complexes. We used the stopped‐flow and microsecond freeze‐hyperquenching (MHQ) techniques supported by steady‐state spectroscopic and electrochemical data to demonstrate the formation of partially coordinated intermediate CuII complexes formed by glycyl–glycyl–histidine (GGH) peptide, the simplest ATCUN/NTS model. One of these novel intermediates, characterized by two‐nitrogen coordination, t1/2≈100 ms at pH 6.0 and the ability to maintain the CuII/CuI redox pair is the best candidate for the long‐sought reactive species in extracellular copper transport.