Rapid measurement of heteronuclear transverse relaxation rates using non-uniformly sampled <i>R</i><sub>1<i>ρ</i></sub> accordion experiments

Abstract. Multidimensional, heteronuclear NMR relaxation methods are used extensively to characterize the dynamics of biological macromolecules. Acquisition datasets on proteins typically requires significant measurement time, often several days. Accordion spectroscopy offers a powerful means shorten rate measurements by encoding “relaxation dimension” into indirect evolution period in multidimensional experiments. Time savings can also be achieved non-uniform sampling (NUS) data, which is increasingly improve spectral resolution or increase sensitivity per unit time. However, NUS not commonly implemented experiments, because most reconstruction algorithms inherently nonlinear, leading problems when estimating signal intensities, constants and their error bounds. We have previously shown how avoid these shortcomings combining accordion with NUS, followed data using sparse exponential mode analysis, thereby achieving dramatic decrease total length longitudinal Here, we present corresponding transverse experiment, taking account special considerations required for its successful implementation framework accordion-NUS approach. attain highest possible precision optimizing scheme respect Cramér–Rao lower bound variance estimated parameter, given number points spectrum-specific characteristics. The resulting R1ρ experiment achieves comparable parameter estimates compared conventional CPMG (Carr–Purcell–Meiboom–Gill) R2 spin-lock experiments while saving an order magnitude