Detection of individual carbon resonances in solid proteins

Cross-polarization dynamics in polycrystalline samples

“…It has long been known that, at low-to-moderate magnetic fields, the dipolar coupling of the 14 N with its quadrupole moment to neighboring 13 C atoms can be observed in the 13 C spectrum [34][35][36]. That this coupling to 14 N is not the source of non-monotonic behavior is shown in Figure 8, in which non-monotonic behavior is observed for the methylene resonance in 98% 15 N-labeled H-glycine.…”

Setting up 13C CP/MAS experiments

“…A close examination at the methylene resonance shows the dipolar coupling (22)(23)(24)(25) of the 14 N with its quadrupole moment to the 13 C, as shown in Figure 16. In essence, when the 14 N nuclei have electric quadrupole interactions comparable to the size of their Zeeman interactions, the quadrupolar interaction mixes the pure Zeeman states of the quadrupolar nucleus.…”

HCN polymers characterized by SSNMR: Solid state reaction of crystalline tetramer (diaminomaleonitrile)

“…In addition, double cross polarization ͑DCP͒ spectra, 10 entailing an additional transfer of polarization from 13 C to 15 N were used to assign the signals of 15 N nuclei bound to 13 C nuclei in mixed-labeled samples. For delay-without-decoupling ͑Dw/oD͒ spectra, 1 H decoupling was turned off between cross polarization and data acquisition to dephase signals a͒ Present address: School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332. from nuclei bonded to 1 H. 11,12 All spectra were acquired on a 360 MHz ͑ 1 H frequency͒ spectrometer ͑Cambridge Instruments͒, using a 4 mm MAS probe ͑Varian͒ operated at 10 kHz. Samples ͑typically 50 mg͒ were sealed under argon in rotor inserts purchased from Wilmad.…”