Shimokawa S, Yokono T, Sohma J
Biochim Biophys Acta. 1976 Mar 17;425(3):349-55. doi: 10.1016/0005-2787(76)90262-8.
13C spin-lattice relazation times (T1 values) in cytidine were determined experimentally to investigate molecular motions of both metal-free and ion-complexed cytidines in dimethylsulfoxide solutions. It was found that the correlation times of the protonated carbons were equal within experimental error, and this equality of correlation times of different sites of the molecule suggests strongly isotropic random motion of the molecule. Correlation times for internal motion of the amino group obtained from the observed T1 of the amino protons are 4.6 -10(-11) S, 2.0 - 10(-9) S and 1.1 - 10(-10) S for the metal-free cytidine and the cytidine complexed with either CaCl2 or ZnCl2, respectively. An experimental value of T1 of the H6 proton of the cytidine base agrees very well with the value estimated from a conformation determined by the nuclear "Overhauser" effect. Spin-lattice relaxation time measurements of the 7Li nucleus in the LiCl/cytidine system strongly suggested that the 7Li cation is directly coordinated with cytidine.
通过实验测定了胞苷中的13C自旋晶格弛豫时间（T1值），以研究二甲基亚砜溶液中无金属和离子络合胞苷的分子运动。结果发现，在实验误差范围内，质子化碳的相关时间相等，分子不同位点相关时间的这种相等强烈表明分子的各向同性随机运动。从氨基质子的观测T1得到的氨基内部运动的相关时间，对于无金属胞苷、与CaCl2或ZnCl2络合的胞苷分别为4.6 - 10（-11）秒、2.0 - 10（-9）秒和1.1 - 10（-10）秒。胞苷碱基H6质子的T1实验值与通过核“Overhauser”效应确定的构象所估计的值非常吻合。LiCl/胞苷体系中7Li核的自旋晶格弛豫时间测量强烈表明7Li阳离子与胞苷直接配位。
