3D NMR experiments for measuring 15N relaxation data of large proteins:: Application to the 44 kDa ectodomain of SIV gp41

A suite of 3D NMR experiments for measuring N-15-{H-1} NOE, N-15 T-1, and N-15 T-1 rho values in large proteins, uniformly labeled with N-15 and C-13, is presented. These experiments are designed for proteins that exhibit extensive spectral overlap in the 2D H-1-N-15 HSQC spectrum. The pulse sequences are readily applicable to perdeuterated samples, which increases the spectral resolution and signal-to-noise ratio, thereby permitting the characterization of protein dynamics to be extended to larger protein systems. Application of the pulse sequences is demonstrated on a perdeuterated C-13/N-15-labeled sample of the 44 kDa ectodomain of SIV gp41.