Figure 2.

(a) NMR spectrum of α₃D (¹H,¹³C-CT–heteronuclear single-quantum coherence) illustrating the assignments of the methyl groups. Prochiral assignments of the methyl groups of valine and leucine were obtained by using a 10% ¹³C labeled sample (35). (b) Summary of the α₃D sequential NOEs. The size of the bar corresponds to the intensity of the NOE. The NOEs were taken from the ¹⁵N- and ¹³C-resolved nuclear Overhauser effect spectroscopy spectra. The three bond ³J_αN coupling constants determined for α₃D are displayed as filled circles and boxes corresponding to ³J_αN coupling constants <6.0 Hz or >8.0 Hz, respectively.