A suite of pulse sequences based on multiple sequential acquisitions at one and two radiofrequency channels for solid-state magic-angle spinning NMR studies of proteins
Abstract
One of the fundamental challenges in the application of solid-state NMR is its limited sensitivity, yet a majority of experiments do not make efficient use of the limited polarization available. The loss in polarization in a single acquisition experiment is mandated by the need to select out a single coherence pathway. In contrast, sequential acquisition strategies can encode more than one pathway in the same experiment or recover unused polarization to supplement a standard experiment. In this article, we present pulse sequences that implement sequential acquisition strategies on one and two radiofrequency channels with a combination of proton and carbon detection to record multiple experiments under magic-angle spinning. We show that complementary 2D experiments such as \(\hbox {C}_{\mathrm{x}} \hbox {H}_{\mathrm{x}}\) and \(\hbox {NH}_{\scriptscriptstyle {\mathrm{N}}}\) or DARR and \(\hbox {NH}_{\scriptscriptstyle {\mathrm{N}}}\) , and 3D experiments such as \(\hbox {NC}_\upalpha \hbox {H}_\upalpha\) and \(\hbox {C}_\upalpha \hbox {NH}_{\scriptscriptstyle {\mathrm{N}}}\) , or \(\hbox {NC}_\upalpha \hbox {C}_{\mathrm{x}}\) and \(\hbox {C}_\upalpha \hbox {NH}_{\scriptscriptstyle {\mathrm{N}}}\) Â* can be combined in a single experiment to ensure time savings of at least 40Â*%. These experiments can be done under fast or slow-moderate magic-angle spinning frequencies aided by windowed \(^{1}\hbox {H}\) acquisition and homonulcear decoupling. The pulse sequence suite is further expanded by including pathways that allow the recovery of residual polarization, the so-called â??afterglowâ?? pathways, to encode a number of pulse sequences to aid in assignments and chemical-shift mapping.
Source: Journal of Biomolecular NMR