Fig. 2.

FPOP labeling of prefusion and postfusion PIV5 F-GCNt. (A) Comparison of the extent of oxidative modification observed in the tryptic peptides of PIV5 F-GCNt labeled in either the prefusion (red bars) or postfusion (blue bars) conformation. Error bars represent ±1 SEM. P values were calculated using an unpaired Student t test and corrected for multiple hypothesis testing using the Benjamini–Hochberg method (*P < 0.05; **P < 0.01; ***P < 0.001; otherwise, P > 0.05). (B and C) The FPOP oxidation data mapped onto the prefusion PIV5 F crystal structure (B) and postfusion homology structure (C). B factor values in the .pdb files were replaced by the corresponding background-subtracted FPOP oxidation values for each tryptic peptide, and one protomer for each was modeled using the Pymol preset “B factor putty.” Peptides with the highest oxidation are depicted with thick red tubing; peptides with low oxidation are depicted with thin blue tubing. The other two protomers in each trimer are represented as ghosted surfaces for clarity. The hydrophobic FP is indicated in B and C by a black arrow. Peptides in the center of the globular head that undergo a dramatic decrease in oxidation between the prefusion and postfusion states are indicated by black arrowheads.