Extended Data Fig. 1: Mass spectrometry characterization of E51 Fab.
From: Asymmetric opening of HIV-1 Env bound to CD4 and a coreceptor-mimicking antibody
a, Peak fractions from anion exchange chromatography of E51 Fab. b, Mass spectra of the three E51 peaks from panel a. The molecular mass for Peak 1 corresponded within 27 Da to the predicted mass for unmodified E51 Fab (48,791 Da), suggesting this E51 Fab fraction contained no sulfated tyrosines. The molecular masses for Peaks 2 and 3 were each increased by 80 Da from the preceding peak, corresponding to the molecular weight of a SO3− group (80 Da). These results are consistent with the identification of Peaks 2 and 3 as E51 Fab with one and two sulfated tyrosines, respectively. Peak 3 was used for preparing complexes for cryo-EM.
