Investigation of electron transfer and effects of post-translational modification in Cu, Zn superoxide dismutase.

Mutations in the gene expressing the metalloenzyme copper, zinc superoxide dismutase (SOD1) are associated with the neurodegenerative disease amyotrophic lateral sclerosis (ALS). Approximately 20% of SOD1 mutations are responsible for familial ALS and it is still unclear as to the exact mechanism as to how the mutated protein develops a toxic gain of function. The first part of this dissertation explores the electron transfer in SOD1 and how charge regulation of the protein is affected by the movement of an electron. The overall net charge of SOD1 showed no change during electron movement in the copper catalytic site, regardless of the oxidation state of copper, due to the protein experiencing complete charge regulation. The second part investigates how post-translational modification of SOD1, specifically cysteine oxidation, affected the heterodimerization of wild-type (WT) and mutant SOD1. The oxidation of cysteine 111 in WT was found to promote heterodimerization between WT and mutant SOD1, and computational simulations showed cysteine oxidation promoted heterodimerization via long range allosteric perturbations.