Fig. 1.

Molecular structure and native mass spectrometry of Etanercept. a Schematic illustration of dimeric Etanercept consisting of a TNFR and an Fc domain. Disulfide bonds in the Fc region are indicated as yellow lines; disulfide bridges in the TNFR domain are not shown. Monosaccharide symbols are listed. Exemplary cleavage sites of IdeS, PNGase F and sialidase are indicated. Native mass spectra of b intact Etanercept (R_set = 17,500 at m/z 200), d Etanercept digested with sialidase or f PNGase F (R_set = 35,000 at m/z 200), and h a combination of PNGase F/sialidase, respectively (R_set = 70,000 at m/z 200). Charge states are indicated. Zooms into the most abundant charge states are shown in c, e, g, and i