Abstract A pair of 3D HNCO-based experiments have been developed with the aim of optimizing the precision of measurement of 1JNH couplings. Both pulse sequences record 1JNH coupling evolution during the entire constant time interval that 15N magnetization is dephasing or rephasing with respect to the directly bonded 13Cā?² nucleus, with 15N13Cā?² multiple quantum coherence maintained during the 13Cā?² evolution period. The first experiment, designed for smaller proteins, produces an apparent doubling of the 1JNH coupling without any accompanying increases in line width. The second experiment is a J-scaled TROSY-HNCO experiment in which the 1JNH coupling is measured by frequency difference between resonances offset symmetrically about the position of the downfield component of the 15N doublet (i.e. the TROSY resonance). This experiment delivers significant gains in precision of 1JNH coupling measurement compared to existing J-scaled TROSY-HNCO experiments. With the proper choice of acquisition parameters and sufficient sensitivity to acquire a 3D TROSY-HNCO experiment, it is shown that 1JNH couplings can be measured with a precision which approaches or exceeds the precision of measurement with which the frequency of the TROSY resonance itself can be determined.
- Content Type Journal Article
- DOI 10.1007/s10858-009-9391-2
- Authors
- Luke Arbogast, Johns Hopkins University Department of Chemistry 3400 North Charles Street Baltimore MD 21218 USA
- Ananya Majumdar, Johns Hopkins University Department of Chemistry 3400 North Charles Street Baltimore MD 21218 USA
- Joel R. Tolman, Johns Hopkins University Department of Chemistry 3400 North Charles Street Baltimore MD 21218 USA
Source: Journal of Biomolecular NMR