Figure 7.

Disruption of the ⁴²RRR⁴⁴ exosite increases dynamics of caspase-6 variants in NTD, 240's regions. A and B, caspase-6, R42–44A, or R44K incubated in D₂O and monitored for exchange over time. Difference plots generated by subtracting the deuterium uptake profiles of common peptides of WT caspase-6 from peptides from either R42–44A (A) or R44K (B) variants. Regions depicted in blue (negative) are less exchanging in the variant than in the WT, whereas regions in red (positive) were more exchanging in the variant than in WT based on the error of the data sets ±0.42 or ±0.73 for the R42–44A or R44K based on the 98 and 95% confidence interval, respectively. C and D, exchange differences mapped to the structure of caspase-6 (predicted with MODELLER to incorporate all amino acids not visible in known structures (55)) of the R42–44A (C) or R44K (D) variants. E, relative deuterium uptake difference scale. F–L, important peptides identified as significantly different upon exchange compared with the WT peptides. Experiments were repeated on 2 different days. Δ indicates the difference, wherein the data from WT is always subtracted from the data from the indicated variant. In all cases, the caspase-6 variants are the ΔN D179CT form.