FIGURE 5.

Identification of disulfide and sulfane sulfur modification of the M. jannaschii SepCysS by LC-MS/MS. Fragment b- and y-ions derived from the tryptic peptide ⁵³AVYEYWDGYSVCDYCHGR⁷⁰ (theoretical MH²⁺ = 1094.20) are labeled in green and blue, respectively. A, MS/MS fragmentation spectra of the −2 Da shifted precursor ion (MH²⁺ = 1093.53). Detected fragment b- and y-ions containing Cys⁶⁴ and Cys⁶⁷ with −2 Da shift are underlined. B, MS/MS fragmentation spectra of the +30 Da shifted precursor ion (MH²⁺ = 1109.56). Detected fragment b- and y-ions containing Cys⁶⁴ and Cys⁶⁷ with +30 Da shift are underlined.