SOD1 and amyotrophic lateral sclerosis: Indeed, in the native conformation (metal bound, disulfide bonded form) most ALS-associated SOD1 variants have high melting temperatures, however, when reduced and metal-free, some variants, such as SOD1G93A, melt below physiological temperature (Furukawa and O'Halloran, 2005; Rodriguez et al., 2005).