Long-range (1)H-(15)N heteronuclear shift correlation at natural abundance.
Despite the inherently low sensitivity of (15)N NMR because of its low gyromagnetic ratio (gamma(N)) and its relatively low natural abundance (0.37%), this important nuclide still has useful potential as a structural probe even at natural abundance. Inverse-detected NMR methods coupled with major advances in NMR probe designs have made it possible to acquire long-range (1)H-(15)N heteronuclear shift correlation data on samples as small as a micromole overnight. Chemical shift referencing schemes for (15)N and the range of (15)N shifts are discussed, followed by a discussion of the currently available pulse sequences, pulse calibration, parametrization and processing of long-range (1)H-(15)N data, and the implications of probe selection. These topics are followed by a review of the applications contained in the literature that have utilized (1)H-(15)N heteronuclear shift correlation experiments at natural abundance, with emphasis placed on the observed long-range coupling pathways.
Martin
G E
GE
Rapid Structure Characterization Group, Pharmaceutical Development, Pharmacia & Upjohn, Kalamazoo, Michigan 49001-0199, USA. gary.e.martin@am.pnu.com
Hadden
C E
CE
D002138:Calibration; D006859:Hydrogen / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D009584:Nitrogen / Q000737:chemistry*
D006859:Hydrogen; D009584:Nitrogen