Multiple-Quantum J-Resolved NMR Spectroscopy (MQ-JRES): Measurement of Multiple-Quantum Relaxation Rates and Relative Signs of Spin Coupling Constants
✍ Scribed by Maili Liu; Xu Zhang
- Publisher
- Elsevier Science
- Year
- 2000
- Tongue
- English
- Weight
- 84 KB
- Volume
- 146
- Category
- Article
- ISSN
- 1090-7807
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✦ Synopsis
The technique of multiple-quantum J-resolved NMR spectroscopy (MQ-JRES) is introduced and applied to the spin system SI 3 -M (such as in the example given here, the 13 CH 3 -12 CH in alanine). The SI 3 spin system was excited to its highest quantum state (8S y I x I y I y ), which consists of four coherences: quadruple quantum of (3I ؉ S), double quantum of (3I ؊ S), double quantum of (I ؉ S), and zero quantum of (I ؊ S). In the MQ spectrum generated from the projection onto the F 1 dimension, the resonances of the different multiple-quantum coherences are resolved by their coupling constants to the remote spin (M). The absorptive lineshapes in both F 1 and F 2 dimensions enable accurate measurements of transverse relaxation rates, and both amplitude and relative signs of the long-range coupling constants are to be derived from either frequency or time domain data. The selective detection of MQ-JRES spectra of the individual MQ coherences using either phase cycling or pulsed field gradients is presented.