Efficient low-power heteronuclear decoupling in 13C high-resolution solid-state NMR under fast magic angle spinning

@article{citeulike:2194638, abstract = {The use of a low-power two-pulse phase modulation (TPPM) sequence is proposed for efficient 1H radio frequency (rf) decoupling in high-resolution 13C solid-state NMR (SSNMR) under fast MAS conditions. Decoupling efficiency for different low-power decoupling sequences such as continuous-wave (cw), TPPM, XiX, and ?-pulse (PIPS) train decoupling has been investigated at a spinning speed of 40 kHz for 13C CPMAS spectra of uniformly 13C- and 15N-labeled L-alanine. It was found that the TPPM decoupling sequence, which was originally designed for high-power decoupling, provides the best decoupling efficiency at low power among all the low-power decoupling sequences examined here. Optimum performance of the low-power TPPM sequence was found to be obtained at a decoupling field intensity (?1) of ??R/4 with a pulse flip angle of ?? and a phase alternation between ± \&phis;(\&phis; = ?20° ), where ?R/2? is the spinning speed. The sensitivity obtained for 13CO2-, 13CH, and 13CH3 in L-alanine under low-power TPPM at ?1/2? of 10 kHz was only 5-15\% less than that under high-power TPPM at ?1/2? of 200 kHz, despite the fact that only 0.25\% of the rf power was required in low-power TPPM. Analysis of the 13CH2 signals for uniformly 13C- and 15N-labeled L-isoleucine under various low-power decoupling sequences also confirmed superior performance of the low-power TPPM sequence, although the intensity obtained by low-power TPPM was 61\% of that obtained by high-power TPPM. 13C CPMAS spectra of 13C-labeled ubiquitin micro crystals obtained by low-power TPPM demonstrates that the low-power TPPM sequence is a practical option that provides excellent resolution and sensitivity in 13C SSNMR for hydrated proteins. Copyright {\copyright} 2007 John Wiley \& Sons, Ltd.}, address = {Department of Chemistry, University of Illinois at Chicago, 845 W. Taylor Street, Chicago, IL 60607, USA}, author = {Kotecha, Mrignayani and Wickramasinghe, Nalinda P. and Ishii, Yoshitaka }, citeulike-article-id = {2194638}, doi = {http://dx.doi.org/10.1002/mrc.2151}, journal = {Magnetic Resonance in Chemistry}, keywords = {mas, ssnmr}, number = {S1}, pages = {S221--S230}, posted-at = {2008-01-04 14:22:22}, priority = {2}, title = {Efficient low-power heteronuclear decoupling in 13C high-resolution solid-state NMR under fast magic angle spinning}, url = {http://dx.doi.org/10.1002/mrc.2151}, volume = {45}, year = {2007} }

TY - JOUR ID - citeulike:2194638 L3 - citeulike-article-id:2194638 TI - Efficient low-power heteronuclear decoupling in 13C high-resolution solid-state NMR under fast magic angle spinning JF - Magnetic Resonance in Chemistry VL - 45 IS - S1 SP - S221 EP - S230 AD - Department of Chemistry, University of Illinois at Chicago, 845 W. Taylor Street, Chicago, IL 60607, USA N2 - The use of a low-power two-pulse phase modulation (TPPM) sequence is proposed for efficient 1H radio frequency (rf) decoupling in high-resolution 13C solid-state NMR (SSNMR) under fast MAS conditions. Decoupling efficiency for different low-power decoupling sequences such as continuous-wave (cw), TPPM, XiX, and ?-pulse (PIPS) train decoupling has been investigated at a spinning speed of 40 kHz for 13C CPMAS spectra of uniformly 13C- and 15N-labeled L-alanine. It was found that the TPPM decoupling sequence, which was originally designed for high-power decoupling, provides the best decoupling efficiency at low power among all the low-power decoupling sequences examined here. Optimum performance of the low-power TPPM sequence was found to be obtained at a decoupling field intensity (?1) of ??R/4 with a pulse flip angle of ?? and a phase alternation between ± &phis;(&phis; = ?20° ), where ?R/2? is the spinning speed. The sensitivity obtained for 13CO2-, 13CH, and 13CH3 in L-alanine under low-power TPPM at ?1/2? of 10 kHz was only 5-15% less than that under high-power TPPM at ?1/2? of 200 kHz, despite the fact that only 0.25% of the rf power was required in low-power TPPM. Analysis of the 13CH2 signals for uniformly 13C- and 15N-labeled L-isoleucine under various low-power decoupling sequences also confirmed superior performance of the low-power TPPM sequence, although the intensity obtained by low-power TPPM was 61% of that obtained by high-power TPPM. 13C CPMAS spectra of 13C-labeled ubiquitin micro crystals obtained by low-power TPPM demonstrates that the low-power TPPM sequence is a practical option that provides excellent resolution and sensitivity in 13C SSNMR for hydrated proteins. Copyright © 2007 John Wiley & Sons, Ltd. KW - mas KW - ssnmr AU - Kotecha, Mrignayani AU - Wickramasinghe, Nalinda AU - Ishii, Yoshitaka PY - 2007/// UR - http://dx.doi.org/10.1002/mrc.2151 ER -