FIGURE 3.

Mass spectrometric analyses of tryptic peptides of CpeA-PEB produced with CpeY and CpeZ. A, MALDI MS/MS spectrum of the m/z 935 precursor ion derived from peptides resulting from the tryptic digestion of the covalent complex CpeA-PEB. This m/z 935 precursor ion was deduced to be a peptide fragment with a covalently bound PEB chromophore. B, fragmentation pattern and corresponding mass assignments for data in panel A. A tick mark prior to number, e.g. ′470, indicates one hydrogen has been transferred to the departing neutral upon cleavage. A tick mark after number, e.g. 814′, indicates the transfer of one hydrogen to the formed ion. A (·) indicates a radical ion.