A QuantitativeJ-Correlation Experiment for the Accurate Measurement of One-Bond Amide15N–1H Couplings in Proteins

✍ Scribed by J.R. Tolman; J.H. Prestegard

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 177 KB
• Volume: 112
• Category: Article
• ISSN: 1064-1866
• DOI: 10.1006/jmrb.1996.0138

✦ Synopsis

Very precise measurements of 1 J NH couplings have been made J-resolved experiment, the selective-coupling-enhanced for approximately 40% of the amide sites in cyanometmyoglobin HSQC (SCE-HSQC) experiment, which allows one-bond using two different experimental approaches. The first approach amide couplings to be measured in the indirectly detected is a previously described frequency-based method in which the frequency domain. Measurement in the indirect domain is couplings are observed as splittings in the frequency-domain specdesirable due to favorable spin-relaxation characteristics and trum. The second is a new approach, along the lines of quantitative the reduction in numbers of homonuclear couplings. How-J-correlation spectroscopy, in which the coupling is encoded in ever, the experiments are limited by the necessity of acquirthe resonance intensity. Measurements obtained from the two exing points over a time scale on the order of T 2 , at a rate perimental techniques are in agreement to a high degree of precidictated by the spectral width. Since these points are acquired sion (s.d. of 0.17 Hz) and residual deviations appear to be largely one per acquisition, a large number of points translates to a random. The new method offers substantial time savings when resonances are widely dispersed in the frequency domain and may large time investment. Broad lines reduce the number of offer improved precision in these instances. ᭧ 1996 Academic Press, Inc. required points but also make frequency-domain measurements more difficult, thereby degrading precision. Quantitative J-correlation experiments overcome some of the above problems by encoding the coupling in the reso-* To whom correspondence should be addressed.