Reduction of RF-induced sample heating with a scroll coil resonator structure for solid-state NMR probes

摘要

Heating due to high power H-1 decoupling limits the experimental lifetime of protein samples for solid-state NMR (SSNMR). Sample deterioration can be minimized by lowering the experimental salt concentration, temperature or decoupling fields; however, these approaches may compromise biological relevance and/or spectroscopic resolution and sensitivity. The desire to apply sophisticated multiple pulse experiments to proteins therefore motivates the development of probes that utilize the RF power more efficiently to generate a high ratio of magnetic to electric field ill the sample. Here a novel scroll coil resonator structure is presented and compared to a traditional solenoid. The scroll coil is demonstrated to be more tolerant of high sample salt concentrations and cause less RF-induced sample treating. With it, the viable experimental lifetime of a microcrystalline ubiquitin sample has been extended by more than an order of magnitude. The higher B, homogeneity and permissible decoupling fields enhance polarization transfer efficiency in N-15-C-13 correlation experiments employed for protein chemical shift assignments and structure determination. (C) 2004 Elsevier Inc. All rights reserved.