Redox state of Troponin C Cysteine in the D/E helix alters the C-domain affinity for the thin filament of vertebrate striated muscle

► TnC affinity for the thin filament is sensitive to the redox state. ► DTT prevents TnC dissociation from the thin filament. ► H2O2 increases TnC dissociation from the thin filament. ► DTT does not affect TnC-C98L dissociation from the thin filament. ► Cys 98 in the D/E helix of TnC helps to anchor it to the thin filament.