Extreme Light Infrastructure-Nuclear Physics ELI-NP, Laser Gamma Experiments Department (LGED), "Horia Hulubei" National Institute for Physics and Nuclear Engineering IFIN-HH, 30 Reactorului Street, 077125 Bucharest-Măgurele, Romania.
Interdisciplinary School of Doctoral Studies, University of Bucharest, Regina Elisabeta Boulevard, 050663 Bucharest, Romania.
J Phys Chem Lett. 2022 Jul 28;13(29):6731-6736. doi: 10.1021/acs.jpclett.2c01749. Epub 2022 Jul 18.
Nuclear magnetization storage, once limited by longitudinal and transverse relaxation lifetimes, and , can be prolonged by symmetry-adapted nuclear spin order, i.e. long-lived states (LLS) and long-lived coherences (LLC), which have significantly extended relaxation time constants compared to and , respectively. Excitation and/or detection of LLS currently involves pulses covering wide frequency ranges in high-magnetic-field spectrometers. This leads to excitation of unwanted signals that may overlap and interfere with the resonances of interest. Herein, we present a new pulse sequence that converts longitudinal magnetization to LLS and further to detectable magnetization using only frequency-selective pulses. We demonstrate the suitability of this sequence for different -coupled spin pairs in dipeptide AlaGly and protein Ubiquitin. The newly developed method is adapted for investigations of LLS in complex systems such as proteins and mixtures of metabolites where selected molecular groups are to be investigated separately.
核磁化存储曾经受到纵向和横向弛豫寿命的限制，分别为 和 。通过对称适应的核自旋有序，即长寿命态（LLS）和长寿命相干性（LLC），可以延长弛豫时间常数，与 和 相比，分别显著延长了弛豫时间常数。目前，LLS 的激发和/或检测涉及在高磁场光谱仪中覆盖宽频率范围的脉冲。这会导致激发不需要的信号，这些信号可能会重叠并干扰感兴趣的共振。在此，我们提出了一种新的脉冲序列，该序列仅使用频率选择性脉冲将纵向磁化转换为 LLS，并进一步转换为可检测的磁化。我们证明了该序列在不同 -耦合自旋对二肽 AlaGly 和蛋白质泛素中的适用性。新开发的方法适用于蛋白质和代谢物混合物等复杂系统中的 LLS 研究，其中要分别研究选定的分子基团。
