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 (13)C, (15)N labeled proteins. These new experiments exploit the simultaneous cross-polarization (SIM-CP) from (1)H to (13)C and (15)N to acquire two 3D experiments simultaneously. This is made possible by bidirectional polarization transfer between (13)C and (15)N and the long living (15)N 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-(13)C,(15)N ubiquitin. The DUMAS approach is general and applicable to many 3D experiments, nearly doubling the performance of NMR spectrometers.