Generation of impossible cross-peaks between bulk water and biomolecules in solution NMR.
Intermolecular multiple-quantum coherences between bulk water and a glycoprotein fragment at modest concentration (20 mM) have been experimentally produced and detected, although such coherences are inconceivable in the normal theoretical framework of nuclear magnetic resonance. A density matrix treatment explains these results by including the long-range dipolar interaction between spins and by discarding the high-temperature approximation. These results imply that peak intensities (critical for structural determinations) can be distorted in many gradient experiments, and show that magic-angle gradients provide substantial improvements with reduced gradient strengths. They also suggest methods for contrast enhancement in magnetic resonance imaging.
Warren
W S
WS
Department of Chemistry, Princeton University, NJ 08544-1009.
Richter
W
W
Andreotti
A H
AH
Farmer
B T
BT
D005353:Fibronectins / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D010446:Peptide Fragments / Q000737:chemistry; D012996:Solutions; D014867:Water / Q000737:chemistry*
D005353:Fibronectins; D010446:Peptide Fragments; D012996:Solutions; D014867:Water