Division of Bioengineering and Bioinformatics, Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Japan.
Department of Structural Biology, Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan; Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo, Japan.
J Magn Reson. 2018 Nov;296:85-92. doi: 10.1016/j.jmr.2018.08.009. Epub 2018 Aug 29.
Side-arm parahydrogen induced polarization (PHIP-SAH) presents a cost-effective method for hyperpolarization of C metabolites (e.g. acetate, pyruvate) for metabolic MRI. The timing and efficiency of typical spin order transfer methods including magnetic field cycling and tailored RF pulse sequences crucially depends on the heteronuclear J coupling network between nascent parahydrogen protons and C, post-parahydrogenation of the target compound. In this work, heteronuclear J (1 < n ≤ 5) couplings of acetate and pyruvate esters pertinent for PHIP-SAH were investigated experimentally using selective HSQMBC-based pulse sequences and numerically using DFT simulations. The CLIP-HSQMBC technique was used to quantify 2/3-bond J couplings, and 4/5-bond J ≲ 0.5 Hz were estimated by the sel-HSQMBC-TOCSY approach. Experimental and numerical (DFT-simulated) J couplings were strongly correlated (P < 0.001). Implications for C hyperpolarization by magnetic field cycling, and PH-INEPT and ESOTHERIC type spin order transfer methods for PHIP-SAH were assessed, and the influence of direct nascent parahydrogen proton to C coupling when compared with indirect homonuclear TOCSY-type transfer through intermediate (non-nascent parahydrogen) protons was studied by the density matrix approach.
旁臂仲氢诱导极化（PHIP-SAH）为代谢 MRI 中 C 代谢物（如乙酸盐、丙酮酸）的超极化提供了一种具有成本效益的方法。典型自旋顺序转移方法的时间和效率，包括磁场循环和定制的射频脉冲序列，关键取决于初生仲氢质子和 C 之间的异核 J 耦合网络，即目标化合物的仲氢化后。在这项工作中，使用选择性 HSQMBC 基脉冲序列实验研究了乙酸盐和丙酮酸酯的异核 J（1<n≤5）耦合，使用 DFT 模拟数值研究了异核 J（1<n≤5）耦合。使用 CLIP-HSQMBC 技术来量化 2/3 键 J 耦合，并且通过 sel-HSQMBC-TOCSY 方法估计 4/5 键 J<0.5 Hz。实验和数值（DFT 模拟）J 耦合具有很强的相关性（P<0.001）。评估了磁场循环和 PH-INEPT 和 ESOTHERIC 型自旋顺序转移方法对 PHIP-SAH 的影响，并通过密度矩阵方法研究了当与通过中间（非初生仲氢）质子的间接同核 TOCSY 型转移相比，直接初生仲氢质子与 C 耦合的影响。
