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. 2016 Jan 28;291(13):6967–6981. doi: 10.1074/jbc.M115.673608

FIGURE 2.

FIGURE 2.

Detection of glutathionylation at Cys-15 of DnaK by mass spectrometry. A and B, nano-LC-LTQ-Orbitrap XL analysis of 2553-Da glutathionylated peptide after trypsin digestion. The detected peaks (main panel) correspond to the predicted peptides (inset) where red corresponds to observed N-terminal peptide fragments and blue corresponds to observed C-terminal peptide fragments. C* indicates Cys-15, which undergoes glutathionylation. A, DnaK from GSSG-treated lysates of E. coli cells that had been subjected to oxidative stress; B, DnaK treated with diamide and GSH after purification. A full list of observed thiol modifications is shown in Table 2. For further details, see “Experimental Procedures.” C, MALDI-TOF detection of glutathionylation of DnaK treated with diamide and GSH after purification. Mass spectra for untreated control (DnaK-C) and glutathionylated (DnaK-G) samples are shown.