Orphan Spin Polarization

Abstract

Magic angle spinning solid-state NMR (MAS ssNMR) spectroscopy is a powerful method for structure determination of biomacromolecules that are recalcitrant to crystallization (membrane proteins and fibrils). Conventional multidimensional ssNMR methods acquire one experiment at a time. This approach is time consuming and discards orphan (unused) spin operators. Relatively low sensitivity and poor resolution of protein samples require long acquisition times for multidimensional ssNMR experiments. Here, we describe our recent progress in the development of multiple acquisition solid-state NMR methods for protein structure determination. A family of experiments called Polarization Optimized Experiments (POE) were designed, in which we utilized the orphan spin operators that are discarded in classical multidimensional NMR experiments, recovering them to allow simultaneous acquisition of multiple 2D and 3D experiments, all while using conventional probes with spectrometers equipped with one receiver. Three strategies namely, DUMAS, MEIOSIS, and MAeSTOSO were used for the concatenation of various 2D and 3D experiments. These methods open up new avenues for reducing the acquisition times of multidimensional experiments for biomolecular ssNMR spectroscopy.

NOAH: NMR Supersequences for Small Molecule Analysis and Structure Elucidation

“…Similar experiments for recording two spectra simultaneously have been proposed in labeled protein samples both in liquids [9] and solids. [10] These should be distinguished from time-shared experiments [11] that collect the same type of spectra from different nuclear species, usually 15 N and 13 C, and require doubling the number of scans for each additional spectrum to allow for phase encoding.…”

PHRONESIS: A One‐Shot Approach for Sequential Assignment of Protein Resonances by Ultrafast MAS Solid‐State NMR Spectroscopy

“…Previous multi-acquisition ssNMR experiments utilized two to four pathways originating from SPECIFIC-CP or other NC transfer variants. [19][20][21][22][23][24][25][26][27][28][29][30][31][32] In contrast, the broadband SPECIFIC-CP sequence creates seven different pathways (Figure S8b). The intensities of the CANtr, CONtr, NCAtr, and NCOtr pathways, were 103 %, 72 %, 55 %, and 100 %, respectively, relative to CA and CO SPECIFIC-CP transfers (Figures S5-S6).…”

“…[1][2][3][4][5][6] The past few years have witnessed a significant effort to speed up the ssNMR experiments using ultrafast magic angle spinning (MAS), dynamic nuclear polarization (DNP), paramagnetic relaxation enhancement (PRE), ultra-high-field magnets, and 1 H detected experiments. [7][8][9][10][11][12][13][14][15][16][17][18] Additionally, the introduction of multi-acquisition polarization optimized experiments (POE) has further boosted data acquisition [19][20][21][22][23] for both solution-and ssNMR spectroscopy. [19][20][21][22][23][24][25][26][27][28][29][30][31][32] Indeed, 1 H detection has significantly improved the sensitivity of fast and ultrafast MAS experiments for fully protonated protein samples; however, the broad line widths of the 1 H resonances reduce the spectral resolution.…”

“…[7][8][9][10][11][12][13][14][15][16][17][18] Additionally, the introduction of multi-acquisition polarization optimized experiments (POE) has further boosted data acquisition [19][20][21][22][23] for both solution-and ssNMR spectroscopy. [19][20][21][22][23][24][25][26][27][28][29][30][31][32] Indeed, 1 H detection has significantly improved the sensitivity of fast and ultrafast MAS experiments for fully protonated protein samples; however, the broad line widths of the 1 H resonances reduce the spectral resolution. [8,14,15,33,34] The latter is often exacerbated by conformational heterogeneity, restricting the range of applications of ssNMR spectroscopy.…”

Practical aspects of the simultaneous collection of COSY and TOCSY spectra

“…One strategy refers to the residual magnetization of low‐gamma nuclei that is too weak for direct observation being transferred to high‐gamma nuclei for detection. Examples have been reported in different multidimensional magic angle spinning solid‐state NMR experiments using commercial probes and standard one receiver configuration, in liquid‐state protein NMR applications and also in multiple receiver systems . On the other hand, a set of gradient‐enhanced homonuclear and heteronuclear experiments have demonstrated the feasibility of the afterglow strategy in small‐molecule NMR spectroscopy, where the residual signal originated on the same high‐gamma nuclei can represent 15–20% of the total signal .…”