Fig. 2

g12777 protein has a SOD-like -sandwich fold and binds to Mn²⁺ ion. a The crystal structure of the catalytic domain of the g12777 protein. Bound Mn²⁺ ion and residues involved in disulfide bond formation are indicated with a pink sphere and stick, respectively. Positions of the N and C termini are indicated as letters. b Electrostatic surface potential of g12777 protein. The surface model of g12777 is colored according to the electrostatic surface potential (blue, positive; red, negative; scale from -50 to + 50 kT/e). c Close-up view of the Mn²⁺-binding site. The binding site is comprised from three aspartic acid residues (D92, D98, and D131) and a disulfide bond with close proximity (C91 and C97). d,e Mn²⁺ binding affinity measured by isothermal titration calorimetry. d raw data in seconds e integrated heat values corrected for the heat of dilution and fit to a one-site binding model (solid line)