A QUANTITATIVE J-CORRELATION EXPERIMENT FOR THE ACCURATE MEASUREMENT OF ONE-BOND AMIDE N-15-H-1 COUPLINGS IN PROTEINS

Very precise measurements of (1)J(NH) couplings have been made for app roximately 40% of the amide sites in cyanometmyoglobin using two diffe rent experimental approaches, The first approach is a previously descr ibed frequency-based method in which the couplings are observed as spl ittings in the frequency-domain spectrum, The second is a new approach , along the lines of quantitative J-correlation spectroscopy, in which the coupling is encoded in the resonance intensity. Measurements obta ined from the two experimental techniques are in agreement to a high d egree of precision (s.d. of 0.17 Hz) and residual deviations appear to be largely random, The new method offers substantial time savings whe n resonances are widely dispersed in the frequency domain and may offe r improved precision in these instances. (C) 1996 Academic Press, Inc.