Figure 2.

NMR signal assignment and secondary structure of the PH and BSD1 domains of human TFIIH p62. (A) p62_1–158 construct used in the NMR experiments. (B) ¹H–¹⁵N-HSQC spectrum. Residues 1–103, 104–108 and 109–158 are labeled in black, yellow and blue, respectively. (C) Chemical shift index (CSI) of ¹³Cα, ¹³Cβ and ¹³C′, and identified secondary structure elements. Arrow: β-strand; rectangle; α-helix. The secondary structure identification was performed using the CSI 2.0 (http://csi.wishartlab.com) web server (79). (D) Random coil index (RCI), calculated by using the difference between observed and reference random coil shifts of ¹³Cα, ¹³Cβ, ¹³C′, ¹⁵N and ¹H. RCI should be proportional to the flexibility of the protein backbone (80).