Both recombinant and human IgG2 subclass antibodies have several different disulfide isoforms [1]. These disulfide isoforms have been shown to possess slightly different global structure, thermal stability and biological activities, as revealed by their different behaviors in size exclusion and ion-exchange chromatography, sedimentation coefficient in analytical ultracentrifugation, etc. However, these techniques provided low structural resolution with regard to the molecular global packing. As a consequence, a detailed mapping of the structural difference between different IgG2 disulfide isoforms has not been available. In this work, we employed hydrogen/deuterium exchange mass spectrometry (HDX-MS) to study the conformation of three major purified IgG2 disulfide isoforms including IgG2-A, IgG2-B and IgG2-A2 (A and B forms are shown in Figure 1).
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