Fig. 4.

Chemical shift patterns of helix capping motifs. (a) The average secondary ¹H^N, ¹⁵N, ¹H^α, ¹³C’, ¹³C^α and ¹³C^β chemical shifts are plotted for each of the six consecutive residues (N′, Ncap, N1, N2, N3 and N4, respectively, with the Ncap box motif in black, the bb(i)→sc(i+3) Ncap motif in dark gray, and the sc(i)←bb(i+3) Ncap motif in light gray. (b) Average secondary chemical shifts for each of the six consecutive residues (C3, C2, C1, Ccap, C′, and C″, respectively) involved in a Schellman (dark gray) or αL (light gray) C-terminal helix capping motif.