Solsona Sancho, CarlesKahn, Thomas B.Badilla, Carmen L.Álvarez Zaldiernas, CristinaBlasi Cabús, JoanFernández, Julio M.Alegre-Cebollada, Jorge2021-04-272021-04-272014-09-260021-9258https://hdl.handle.net/2445/176729Neurodegenerative diseases share a common characteristic, the presence of intracellular or extracellular deposits of protein aggregates in nervous tissues. Amyotrophic Lateral Sclerosis (ALS) is a severe and fatal neurodegenerative disorder, which affects preferentially motoneurons. Changes in the redox state of superoxide dismutase 1 (SOD1) are associated with the onset and development of familial forms of ALS. In human SOD1 (hSOD1), a conserved disulfide bond and two free cysteine residues can engage in anomalous thiol/disulfide exchange resulting in non-native disulfides, a hallmark of ALS that is related to protein misfolding and aggregation. Because of the many competing reaction pathways, traditional bulk techniques fall short at quantifying individual thiol/disulfide exchange reactions. Here, we adapt recently developed single-bond chemistry techniques to study individual disulfide isomerization reactions in hSOD1. Mechanical unfolding of hSOD1 leads to the formation of a polypeptide loop held by the disulfide. This loop behaves as a molecular jump rope that brings reactive Cys-111 close to the disulfide. Using force-clamp spectroscopy, we monitor nucleophilic attack of Cys-111 at either sulfur of the disulfide and determine the selectivity of the reaction. Disease-causing mutations G93A and A4V show greatly altered reactivity patterns, which may contribute to the progression of familial ALS.11 p.application/pdfeng(c) American Society for Biochemistry and Molecular Biology, 2014Esclerosi lateral amiotròficaEnzimologiaCisteïnaQuímicaAmyotrophic lateral sclerosisEnzymologyCysteineChemistryinfo:eu-repo/semantics/article6728522021-04-27info:eu-repo/semantics/openAccess25096579