3D DUMAS: Simultaneous acquisition of three-dimensional magic angle spinning solid-state NMR experiments of proteins

Using the DUMAS (Dual acquisition Magic Angle Spinning) solid-state NMR approach, we created new pulse schemes that enable the simultaneous acquisition of three dimensional (3D) experiments on uniformly ¹³C, ¹⁵N labeled proteins. These new experiments exploit the simultaneous cross-polarization (SIM-CP) from ¹H to ¹³C and ¹⁵N to acquire two 3D experiments simultaneously. This is made possible by bidirectional polarization transfer between ¹³C and ¹⁵N and the long living ¹⁵N z-polarization in solid state NMR. To demonstrate the power of this approach, four 3D pulse sequences (NCACX, CANCO, NCOCX, CON(CA)CX) are combined into two pulse sequences (3D DUMAS-NCACX-CANCO, 3D DUMAS-NCOCX-CON(CA)CX) that allow simultaneous acquisition of these experiments, reducing the experimental time by approximately half. Importantly, the 3D DUMAS-NCACX-CANCO experiment alone makes it possible to obtain the majority of the backbone sequential resonance assignments for microcrystalline U-¹³C,¹⁵N ubiquitin. The DUMAS approach is general and applicable to many 3D experiments, nearly doubling the performance of NMR spectrometers.