Fig. 5.

(a) Sequence and secondary structure of WT Im7. Numbering shown is for native Im7, the construct used contains an additional 8 residues at the N-terminus (MEHHHHHH-) for expression and purification purposes [24], [28], [29]. The four helices are coloured (I) red, (II) green, (III) purple, and (IV) yellow. The sites of mutations in DM Im7 are indicated with asterisks and the sites of mutations in TM Im7 with black circles. Residues where oxidation was identified in the three peptides investigated are shown in bold. (b) Peptide level quantification of oxidation levels in DM Im7 and TM Im7 (relative to the corresponding unoxidised peptide in the same sample). Data were normalised to the extent of modification observed in WT Im7 to track changes in the different proteins. Peptide 21–43 from DM Im7 shows no increase in modification extent relative to WT Im7.