Rymdén R, Stilbs P
Biophys Chem. 1985 Feb;21(2):145-56. doi: 10.1016/0301-4622(85)85016-x.
The self-aggregation of the mononucleotides (AMP, CMP, GMP and UMP) and caffeine up to their solubility limit in 2H2O has been monitored through self-diffusion measurements, using the Fourier transform NMR pulsed-gradient spin-echo self-diffusion technique. The data were iteratively fitted to a number of aggregation models. It was concluded that the best agreement between simulations and experiment for the mononucleotides was obtained for a 'semi-isodesmic', indefinite aggregation model (also known as a Type III SEK or cooperative indefinite self-association model), where the first (dimerization) aggregation constant is a magnitude lower than those for the higher aggregation steps. Typical values were 0.4 and 6 l mol-1, respectively. Under these conditions, the main fraction of solute is monomeric throughout the concentration range and the distribution of higher oligomers is very broad. Caffeine self-aggregation is clearly different and is consistent with several aggregation models. The mixed aggregation of caffeine (at a low total concentration) and the mononucleotides was successfully monitored in an extension of the basic study. It was found that caffeine binding to mononucleotide aggregates increases in the series UMP, CMP, GMP and AMP.
通过使用傅里叶变换核磁共振脉冲梯度自旋回波自扩散技术进行自扩散测量，监测了单核苷酸（AMP、CMP、GMP和UMP）与咖啡因在2H2O中直至其溶解度极限的自聚集情况。数据被迭代拟合到多个聚集模型。得出的结论是，对于单核苷酸，模拟与实验之间的最佳一致性是通过“半等键”、不确定聚集模型（也称为III型SEK或协同不确定自缔合模型）获得的，其中第一个（二聚化）聚集常数比更高聚集步骤的常数低一个数量级。典型值分别为0.4和6 l mol-1。在这些条件下，溶质的主要部分在整个浓度范围内都是单体，并且更高寡聚物的分布非常广泛。咖啡因的自聚集明显不同，并且与几种聚集模型一致。在基础研究的扩展中成功监测了咖啡因（在低总浓度下）与单核苷酸的混合聚集。发现咖啡因与单核苷酸聚集体的结合在UMP、CMP、GMP和AMP系列中增加。
