Tilt angle dependence of cross-relaxation in off-resonance ROESY.
We present an efficient experimental method to evaluate whether the effective cross-relaxation rate between a pair of spins vanishes when applying an off-resonance spin-lock field. It is shown that the cross-relaxation rate can be made to vanish even when the two spins concerned resonate at different offsets and experience significantly different tilt angles of their respective spin-lock fields. This is verified experimentally using a sample of 15N-labeled human ubiquitin, through selective excitation of chosen amide protons. The results are relevant for the quantitative interpretation of off-resonance ROESY experiments.
Cutting
B
B
Section de Chime, Université de Lausanne, Lausanne, 1015, Switzerland.
Ghose
R
R
Bodenhausen
G
G
D000577:Amides; D006801:Humans; D009587:Nitrogen Isotopes; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D011522:Protons; D013113:Spin Labels; D014452:Ubiquitins / Q000737:chemistry*
D000577:Amides; D009587:Nitrogen Isotopes; D011522:Protons; D013113:Spin Labels; D014452:Ubiquitins