FIGURE 7.

Peptide mass fingerprinting of CrICL reveals that Cys¹⁷⁸ and Cys²⁴⁷ are glutathionylated. WT CrICL was incubated with 5 mm GSSG for 24 h and dialyzed overnight against HEPES-NaOH (pH 7.2). Peptide mass fingerprints of Glu-C digestions after alkylation of cysteines with iodoacetamide (+57 Da) showed a glutathione adduct (+305 Da) on peptides Asp¹⁷⁰–Glu¹⁹¹ and Gly²⁴⁴–Glu²⁷² (A). For both peptides, the 305-Da mass increase was reversed by DTTred treatment (B). The peptides containing Cys¹⁶⁵ and Cys³⁰¹ were found to be exclusively carbamidomethylated.