Figure 10. Solution NMR data of Mn²⁺, Fe²⁺, Co²⁺ and Ni²⁺-bound HsARD isozymes.

Left: Upfield region of 800 MHz ¹H NMR spectra of Mn-HsARD (pink), Fe-HsARD (red), Co-HsARD (blue), and Ni-HsARD (green) showing methyl resonances of amino acid side chains ring current-shifted by nearby aromatic residues. The different spectral patterns indicate differences in side chain packing in hydrophobic cores. Right: Overlay of the 2D ¹H, ¹⁵N HSQC spectra of Mn-HsARD (pink), Co-HsARD (blue), Fe-HsARD (red) and Ni-HsARD (green). Different shift patterns indicate differences in local hydrogen bonding and structure. All spectra were obtained at 25 °C, pH 7.0 at 800 MHz ¹H observe frequency. Reproduced with permission from Ref. 4. Copyright 2017 Oxford University Press.