Koźmiński W
Department of Chemistry, Warsaw University, ul. Pasteura 1, Warsaw, 02-093, Poland.
J Magn Reson. 1999 Apr;137(2):408-12. doi: 10.1006/jmre.1998.1700.
A new two-dimensional pulse sequence for accurately determining heteronuclear coupling constants is presented. It is derived from HSQC and HECADE techniques with B0 gradient coherence selection. The main feature of the proposed method is spectra with only one component of the IS doublet; i.e., the final result is equivalent to a selective broadband excitation of either Salpha or Sbeta spin states and a preservation of these states during the entire experiment. The effect is obtained by an appropriate combination of in- and antiphase coherences. It is demonstrated that heteronuclear single-bond as well as long-range coupling constants and their relative signs are readily evaluated. The proposed sequence is equally or less sensitive to a variation of heteronuclear one-bond couplings than previously published, closely related sequences. The new method is applied to a peptide sample for determination of 3JN, Hbeta.
本文提出了一种用于精确测定异核耦合常数的新型二维脉冲序列。它是从具有B0梯度相干选择的HSQC和HECADE技术推导而来的。该方法的主要特点是光谱中只有IS双峰的一个分量；即最终结果等同于对Sα或Sβ自旋态进行选择性宽带激发，并在整个实验过程中保持这些状态。通过同相和反相相干的适当组合获得这种效果。结果表明，异核单键以及长程耦合常数及其相对符号都能很容易地得到评估。与先前发表的密切相关序列相比，所提出的序列对异核一键耦合变化的敏感度相同或更低。该新方法应用于肽样品以测定3JN，Hβ。
