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Figure 3.
Structural studies of α-selenoconotoxin ImI analogues.
Circular dichroism spectra (A) and a comparison of the NH (B)
and Hα (C) backbone chemical shifts are shown. WT ImI shifts
from Gehrmann et al. (24) were used. Secondary chemical shifts
were calculated by subtracting random coil values (54) from the
observed chemical shifts. •, WT ImI; ○, [Sec^2,8]ImI; ▴,
[Sec^3,12]ImI; ▵, [Sec^2,3,8,12]ImI. D, overlay of the
backbones (N, Cα, and CO atoms) and of the disulfide and
diselenide bonds of the 20 minimum energy conformers
representing the [Sec^2,8]ImI and [Sec^2,3,8,12]ImI NMR-derived
structures. Disulfide bonds are shown in red, and diselenide
bonds are shown in yellow. E, ribbon representations of
[Sec^2,8]ImI and [Sec^2,3,8,12]ImI. WT ImI is shown for
comparison (25). F, overlays of the minimum energy structures of
[Sec^2,8]ImI and [Sec^2,3,8,12]ImI with WT ImI (left and middle,
respectively) and overlay of [Sec^2,8]ImI on [Sec^2,3,8,12]ImI
(right).
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