Overloop K, Vanstapel F, Van Hecke P
Biomedical NMR Unit, Faculty of Medicine, Katholieke Universiteit Leuven, Belgium.
Magn Reson Med. 1996 Jul;36(1):45-51. doi: 10.1002/mrm.1910360109.
This study is the first report on the multiexponential T2 relaxation of the 13C-1 carbon of glycogen. In contrast to T1 relaxation, which does not display observable multiexponential decay behavior, T2 relaxation is described by a continuous distribution of T2 times. Changes in molecular weight and sample viscosity, which affect the overall mobility of the glycogen particle have little influence on T1 and T2 relaxation times. This is in contradiction with earlier results that T2 is dominated by the overall motion of the glycogen particles [L.-H. Zang Biochemistry 29, 6815-6820 (1990)]. T1 depends strongly on the external field Bo and is almost temperature independent in the range 23-37 degrees C whereas T2 is field independent and varies appreciably with temperature. The experimental T1 and T2 relaxation data are shown to be consistent with existing theoretical models for relaxation, suitably modified to include a distribution of correlation times for the internal motions. The presence of fast decaying components (short T2) in the FID implies broad line components in the frequency spectrum and the corresponding need to appropriately set the integration limits for the quantification of the glycogen peak.
本研究是关于糖原13C-1碳多指数T2弛豫的首份报告。与不显示可观测多指数衰减行为的T1弛豫不同，T2弛豫由T2时间的连续分布来描述。分子量和样品粘度的变化会影响糖原颗粒的整体流动性，但对T1和T2弛豫时间影响很小。这与早期结果相矛盾，早期结果认为T2由糖原颗粒的整体运动主导[臧立华，《生物化学》29，6815 - 6820(1990)]。T1强烈依赖于外场B0，在23 - 37摄氏度范围内几乎与温度无关，而T2与场无关且随温度有明显变化。实验得到的T1和T2弛豫数据与现有的弛豫理论模型一致，这些模型经过适当修改以纳入内部运动相关时间的分布。FID中快速衰减成分（短T2）的存在意味着频谱中有宽线成分，相应地需要适当设置积分限以对糖原峰进行定量。
