Abstract <p>In this commemorative article, Gerhard Wagner recalls his scientific interactions with Alexander Arseniev during his time at ETH Zürich and thereafter. The narrative focuses on their collaborative NMR project to determine the solution structure of rabbit liver metallothionein-2, a protein with no prior crystal or solution structure. Key challenges included correcting errors in the published amino acid sequence and determining how seven metal ions coordinate with twenty cysteine residues. By replacing Zn²⁺ with ¹¹³Cd²⁺ and applying newly developed inverse-detection heteronuclear correlation experiments, crucial cadmium–cysteine connectivities were obtained. Arseniev successfully used Distance Geometry algorithms to calculate the three-dimensional fold, revealing two domains with metal clusters forming the protein’s hydrophobic core. The article also describes the comparison with an initially conflicting crystal structure, leading to a joint publication in PNAS, as well as personal meetings between Wagner and Arseniev in Russia and the United States.</p>