Oxidative misfolding of Cu/Zn-superoxide dismutase triggered by non-canonical intramolecular disulfide formation

Itsuki Anzai, Eiichi Tokuda, Sumika Handa, Hidemi Misawa, Shuji Akiyama, Yoshiaki Furukawa

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


Misfolded Cu/Zn-superoxide dismutase (SOD1) is a pathological species in a subset of amyotrophic lateral sclerosis (ALS). Oxidative stress is known to increase in affected spinal cords of ALS and is thus considered to cause damages on SOD1 leading to the misfolding and aggregation. Despite this, it still remains elusive what triggers misfolding of SOD1 under oxidizing environment. Here, we show that a thiol group of Cys111 in SOD1 is oxidized to a sulfenic acid with hydrogen peroxide and reveal that further dissociation of the bound metal ions from the oxidized SOD1 allows another free Cys residue (Cys6) to nucleophilically attack the sulfenylated Cys111. As a result, an intra-molecular disulfide bond forms between Cys6 and Cys111. Such an abnormal SOD1 with the non-canonical disulfide bond was conformationally extended with significant cytotoxicity as well as high propensity to aggregate. Taken together, we propose a new model of SOD1 misfolding under oxidizing environment, in which formation of the non-canonical intramolecular disulfide bond plays a pivotal role.

Original languageEnglish
Pages (from-to)187-199
Number of pages13
JournalFree Radical Biology and Medicine
Publication statusPublished - 1 Feb 2020
Externally publishedYes


  • Disulfide formation
  • Neurodegenerative diseases
  • Protein misfolding


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