Figure 4.

(A) Square-planar coordination mode of Cu²⁺ to NHCOMe-Gly-Gly-His-CONHMeCu optimized through DFT calculations. (B) Crystallographic structure of copper(II)-glycylglycyl-l-histidine-N-methyl amide complex (ref (39)). (C) A different square-planar coordination mode of Cu²⁺ to NHCOMe-Gly-Gly-His-CONHMeCu optimized through DFT calculations. Steric clash between the imidazole ring and an amide carbonyl group is represented with a yellow star. (D) Cu²⁺-binding loop (coordination mode II) inserted in position 23 of T4 lysozyme, after 2 ns of MD simulation.