Fig. 3: HDX-MS analysis of plasma purified hTTR.
a Bidimensional HDX-MS heatmap of plasma purified hTTR at pH 7.2. For each peptic fragment (blue bars), the %D value at the indicated labeling time (0.5–120 min) is mapped onto the protein sequence. The color key in the heatmap indicates %D, from dark blue (<10%) to light red (>90%). Secondary structure is noted at the bottom of hTTR sequence, along with a thick red arrow indicating the major scissile bond (Leu58-Thr59) for subtilisin and small black arrows indicating minor cleavage sites. The heatmap was generated using 38 single and overlapping fragments (Supplementary Fig. 5). b Three-dimensional HDX-MS heatmap of deuterium uptake by hTTR was obtained by mapping %D values reported in a (30-s H/D exchange time) onto the crystal structure of hTTR (1tta.pdb)2. For clarity, only the monomer structure is shown. Labels (yellow) identify β-strands while the arrows (red) indicate the scissile Leu58Thr59 bond. c Ribbon drawing of hTTR tetramer structure (1tta). The region 59–127 in the interacting (symmetry related) monomers are shown in blue (A, D) and magenta (B, C). The region 1–58 is shown in gray. d Schematic representation of HDX-NMR protection factors (P) of recombinant wild-type hTTR, after 2-h exchange time at pH 5.738. The color key indicates P values: from blue (P > 2.5 × 106) to red (P < 0.5 × 106). Flexible/exposed and rigid/buried regions are characterized by low and high P values, respectively. e Protein disorder profiles of hTTR sequence, according to different prediction methods: IUPre2A75, PONDR-FIT76, and VSL277.
