FIGURE 7.

Model for the regeneration of MSRB1 by the CDSP32 Trx. The first step consists of MetSO reduction with the concomitant release of 1 mol of Met and the formation of a stable sulfenic acid intermediate on catalytic Cys¹⁸⁶ of MSRB1 (1). The sulfenic acid is then attacked by the catalytic Cys²¹⁹ of CDSP32 leading to the liberation of one molecule of water and to the formation of a transient intermolecular disulfide bond (2). Then the resolving Cys²²² of CDSP32 attacks the Cys²¹⁹ to form an intramolecular disulfide bond and release the reduced MSRB1 (3).