Arús C, Westler W M, Bárány M, Markley J L
Biochemistry. 1986 Jun 3;25(11):3346-51. doi: 10.1021/bi00359a038.
A new 1H NMR pulse sequence is described that combines water suppression with the selective observation of signals from coupled spin systems. The pulse sequence is easy to set up and compensates for pulse width inhomogeneity in the biological sample. Suppression of the water signal is achieved by pulses that return the water spins to their equilibrium position; spectral editing is based on the J modulation present in spin-echo spectra and its inhibition by coherent decoupling at one of the resonances of the spin system of interest. The pulse sequence, which was designed for 1H NMR spectroscopy of tissue, was tested at 470 MHz on excised frog muscle and rat brain. The lactate methyl resonance of caffeine-treated frog sartorius muscle was observed selectively by irradiation at the position of its alcoholic proton. The terminal methyl signal of linolenic acid, along with other fatty acids of the linolenic series (first double bond in the omega-3 position), was observed selectively by irradiation at the position of its omega-1 methylene group. 1H NMR spectra of rat brain were edited to reveal the terminal methyl of either linolenic series or all other fatty acids. The results suggest that the terminal methyl groups of fatty acids of the linolenic series (mostly docosahexaenoic acid, 22:6) have higher mobility than those of all other fatty acids.
本文描述了一种新的氢核磁共振脉冲序列，该序列将水抑制与对耦合自旋系统信号的选择性观测相结合。该脉冲序列易于设置，并能补偿生物样品中的脉冲宽度不均匀性。水信号的抑制通过使水自旋回到其平衡位置的脉冲来实现；光谱编辑基于自旋回波光谱中存在的J调制及其在感兴趣自旋系统的一个共振处通过相干去耦的抑制作用。该为组织的氢核磁共振光谱设计的脉冲序列，在470兆赫下对切除的青蛙肌肉和大鼠大脑进行了测试。通过在咖啡因处理的青蛙缝匠肌乳酸甲酯共振的醇质子位置进行照射，选择性地观测到了该共振信号。通过在亚麻酸ω-1亚甲基位置进行照射，选择性地观测到了亚麻酸的末端甲基信号以及亚麻酸系列的其他脂肪酸（第一个双键在ω-3位置）。对大鼠大脑的氢核磁共振光谱进行编辑，以揭示亚麻酸系列或所有其他脂肪酸的末端甲基。结果表明，亚麻酸系列脂肪酸（主要是二十二碳六烯酸，22:6）的末端甲基比所有其他脂肪酸的末端甲基具有更高的流动性。
