title: Cross-correlations between low-γ nuclei in solids via a common dipolar bath.
abstract: Correlation of chemical shifts of low-γ nuclei (such as 15N) is an important method for assignment of resonances in uniformly-labeled biological solids. Under static experimental conditions, an efficient mixing of low-γ nuclear spin magnetization can be achieved by a thermal contact to the common reservoir of dipole-dipole interactions in order to create 15N-15N, 13C-13C, or 15N-13C cross-peaks in a 2D correlation spectrum. A thermodynamic approach can be used to understand the mechanism of magnetization mixing in various 2D correlation pulse sequences. This mechanism is suppressed under magic-angle spinning, when mixing via direct cross-polarization with protons becomes more efficient. Experimental results are presented for single-crystalline and powder samples of 15N-labeled N-acetyl-L-15N-valyl-L-15N-leucine (NAVL). In addition to the thermodynamic analysis of mixing pulse sequences, two different new mixing sequences utilizing adiabatic pulses are also experimentally demonstrated.
authors.affiliation: Biophysics and Department of Chemistry, The University of Michigan, Ann Arbor, MI 48109-1055, USA.
authors.forename: Aanatoly K
authors.initials: AK
authors.lastname: Khitrin
authors.forename: Jiadi
authors.initials: J
authors.lastname: Xu
authors.forename: Ayyalusamy
authors.initials: A
authors.lastname: Ramamoorthy
mesh_terms: D000465:Algorithms; D002247:Carbon Isotopes; D003460:Crystallization; D004151:Dipeptides / Q000737:chemistry; D004574:Electromagnetic Fields; D004601:Elementary Particles; D005720:Gamma Rays; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D009587:Nitrogen Isotopes; D013816:Thermodynamics
chemical_list: D002247:Carbon Isotopes; D004151:Dipeptides; C098112:N-acetylvalylleucine; D009587:Nitrogen Isotopes