Fig. 4.

Heteronuclear NMR spectroscopy of ¹⁵N/¹³C HIV-1 gp120 outer domain. A ¹H-¹H plane of a 3D ¹⁵N edited NOESY HSQC acquired on a ~400 μM ¹⁵N gp120 outer domain at 900 MHz is shown in (a). In b, a ¹H-¹³C projection of a 3D HNCO spectrum acquired on a ~400 μM ¹⁵N/¹³C gp120 outer domain at 900 MHz further demonstrates that the adenovirus-vectored mammalian expression system can provide the necessary isotopically enriched samples for heteronuclear NMR spectroscopy