Thermal stability of metallated and demetallated wildtype SOD1, SOD1^G93A and GFP-SOD1^G93A proteins.

The thermal stability of wildtype SOD1 and SOD1G93A mutants was assessed at two concentrations (11µM and 33µM) and in the metallated and demetallated form (when incubated with 20mM EDTA which functioned as a heavy metal chelator). Protein stability is expressed as apparent Tm, which refers to the mid-point temperature (°C) where the ratio of unfolded to folded proteins is 1∶1. Apparent Tm values reported are the average values±SD obtained from n = 3. Asterisks denote p-values calculated using the two-tailed Student t-test for the paired condition of metallated versus demetallated SOD1, where ** = p<0.005 and *** = p<10−5.