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. 2020 Mar 17;15(3):e0229027. doi: 10.1371/journal.pone.0229027

Fig 2. Identification of an amino acid responsible for low-pH-induced aggregation in human IgG4.

Fig 2

(A) Identification of the domain critical for aggregate formation through domain swapping between IgG1 and IgG4. SEC analysis of the percentage of aggregation following incubation at pH 3.4 for 10 and 60 min at 37°C. (B) Alignment of the CH3 domains of human IgG1 and IgG4. (C) Identification of the amino acid in CH3 domain that is responsible for acid-induced aggregation. (D) Effect of amino acid substitution at position 409 on acid-induced aggregation. (E) Effect of S228P or L235E mutation on acid-induced aggregation. (F) Effect of K370E mutation on acid-induced aggregation. Data are presented as means ± SD of experiments performed in triplicate. Black bars: initial data; gray and white bars: pH 3.4 for 10 and 60 min at 37°C, respectively.