Absence of residual structure in the intrinsically disordered regulatory protein CP12 in its reduced state.

The redox switch protein CP12 is a key player of the regulation of the Benson-Calvin cycle. Its oxidation state is controlled by the formation/dissociation of two intramolecular disulphide bridges during the day/night cycle. CP12 was known to be globally intrinsically disordered on a large scale in its reduced state, while being partly ordered in the oxidised state.