FIGURE 2.

Comparative analysis of fragments P1 and C1 by RP-HPLC-TOF/MS. Purified P1 and C1 generated by incubation with H₂O₂ for 2 and 6 weeks were reduced and alkylated, analyzed by RP-HPLC, and characterized by in-line TOF/MS. Peaks 1–3 were found to be truncated HC of the Fc domain (Fc-HC), peaks 4 and 5 were identified as LC, and peaks 6 and 7 as intact HC. A minor peak shown in the untreated control sample and C1 profiles, labeled with an asterisk, was determined to be an oxidized Fc domain fragment generated by breaking the Asp-Pro (DP) peptide bond in HC of the Fc domain. The corresponding mass data are shown in Table 1. mAU, milliabsorbance unit.