FIGURE 1.

SECs of the partial molecule (P1) and the H₂O₂-induced fragments C1 and C2. A, IgG1-untreated control sample included a partial molecule (P1) eluting after 34.5 min. B, time-dependent formation of the C1 and C2 fragments upon incubation in the presence of H₂O₂. The direction of the chromatographic changes with increasing incubation time is indicated by the arrows. The reaction was carried out at 2 °C in 10 mm glutamic acid buffer, pH 5.2. The fragmentation was initialized by the addition of H₂O₂ to a final concentration of 20 mm and monitored for 21 days. The H₂O₂ treatment was stopped at the noted time points by adding 200 units/ml catalase. AU, absorbance unit.