Fig. 4

Mapping of disulphide-bonds in the Pfs48/45-6C region of R0.6C. R0.6C with and without reduction was digested with the protease trypsin prior to LC–MS/MS analysis. Two crosslinked peptides were identified and corresponding mass spectra of each peptide is shown in a and b with mass spectra corresponding to the non-reduced sample in black and the corresponding mass spectra from the reduced sample in blue. The proposed disulfide connectivity is indicated (green dashed lines) based on the extensive MS/MS fragmentation of each peptide (solid black lines). Several control peptides without cysteine residues were analyzed alongside to confirm equal sample load in each analysis, and spectra for one of these in shown c. Annotated MS/MS spectra of the peptide from a is shown in d. Schematic of the identified disulfide connectivity of Pfs48/45-6C in R0.6C is shown in e. The disulfide bonds that have been verified by LC–MS/MS is indicated by a solid black line and disulfide bonds indicated with dashed green lines is one of two possibilities