Bennett Andrew E, Gross John D, Wagner Gerhard
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Building C-1, Boston, MA 02115, USA.
J Magn Reson. 2003 Nov;165(1):59-79. doi: 10.1016/s1090-7807(03)00244-1.
Experiments which require mixing among spins with large frequency differences are generally performed with sequences based on composite pulses or computer-optimized cycles. Adiabatic pulses generally offer several advantages over other approaches, including greater single spin inversion bandwidths and tolerance to RF inhomogeneity. Here, a novel theoretical framework is presented in order to understand how spin-spin interactions are influenced by adiabatic inversion pulses, and insights from this approach are used to design more efficient adiabatic coherence exchange experiments. For very large frequency differences, this new approach generally offers improved results over previously applied mixing sequences, as applied to 13C-13C experiments which are the basis of modern sidechain assignment techniques in proteins. It is also anticipated that the approach presented here will be applicable to the analysis of various alternative approaches to adiabatic mixing.
需要在具有大频率差的自旋之间进行混合的实验通常使用基于复合脉冲或计算机优化周期的序列来进行。与其他方法相比，绝热脉冲通常具有几个优点，包括更大的单自旋反转带宽和对射频不均匀性的耐受性。在此，提出了一种新颖的理论框架，以了解绝热反转脉冲如何影响自旋-自旋相互作用，并利用该方法的见解来设计更高效的绝热相干交换实验。对于非常大的频率差，这种新方法通常比以前应用的混合序列提供更好的结果，如应用于13C-13C实验，这些实验是现代蛋白质侧链归属技术的基础。还预计这里提出的方法将适用于分析绝热混合的各种替代方法。
