Figure 2.

Overall structures of Ni‐enzymes. (a). CODH dimer from Rhodospirillum rubrum (PDB code: 1JQK). The N‐terminal domain is in magenta and the two Rossman‐like domains are in green and blue. C‐clusters are depicted in spheres B. α₂ß₂ tetramer of CODH/ACS from Moorella thermoacetica (PDB code: 1OAO). The two ß subunits of CODH are colored in blue and cyan. The two ACS subunits are in open or closed conformation. A‐ and C‐clusters are depicted in spheres. C. Archetypical structure of [NiFe]‐hydrogenase from Desulfovibrio gigas (PDB code: 1FRV). The large subunit is in magenta and the small subunit in green. The buried active site is depicted in spheres. D. Dimer of αßɤ MCR from Methanothermobacter marbugensis (PDB code: 3POT). The α, ß, and ɤ subunits are in blue, cyan, and magenta, respectively. Coenzyme F430 is depicted in orange and Coenzyme B in green. E. Ni‐SOD hexamer from Streptomyces seoulensis (PDB code: 1Q0D). (f). Trimer of αßɤ urease from Sporosarcina pasteurii (PDB code: 4CEU). The α, ß, and ɤ subunits are in magenta, blue, and cyan, respectively. Helix‐turn‐helix motif (residues 375–405) belonging to subunit α is highlighted in orange. (g). Closed conformation of LarA from Lactobacillus plantarium (PDB code: 5HUQ). The two domains are in orange and blue and the pincer nucleotide is in magenta. (h). Glyoxalase I dimer from E. coli (PDB code: 1F9Z). (i). Ni‐ARD monomer from Klebsellia oxytoca (PDB code: 1ZRR) α‐helices are in cyan and ß‐strands in magenta. In all structures, nickel ions are depicted as green spheres and FeS clusters are depicted in red and yellow spheres for iron and sulfur atoms, respectively