6264
J. Am. Chem. Soc. 1996, 118, 6264-6272
Magnetic Field Dependence of Nitrogen-Proton J Splittings in 15N-Enriched Human Ubiquitin Resulting from Relaxation Interference and Residual Dipolar Coupling Nico Tjandra, Stephan Grzesiek, and Ad Bax* Contribution from the Laboratory of Chemical Physics, National Institutes of Diabetes and DigestiVe and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0520 ReceiVed January 12, 1996X
Abstract: One-bond 1JNH couplings have been measured in 15N-enriched human ubiquitin and range from 91.1 to 95.6 Hz. Measurements have been carried out using two different methods and at 1H frequencies of 360, 500, and 600 MHz. The best method yields a precision of ca 0.02 Hz, and permits reliable measurement of the small changes (
