Sigel H, Corfù N A
Institute of Inorganic Chemistry, University of Basel, Switzerland.
Eur J Biochem. 1996 Sep 15;240(3):508-17. doi: 10.1111/j.1432-1033.1996.0508h.x.
The occurrence of high concentrations of ATP in certain cell organelles prompted us to study the self-association of ATP via the concentration dependence of the 1H-NMR chemical shifts for H2, H8 and H1' in D2O at pD 8.4 (25 degrees C) in the range 0.0025-0.4 M in the presence and absence of poly(alpha, L-lysine), where [Lys units] was 0.4 M. The experiment in the presence of poly(Lys) was repeated at pD 12.1. At pD 8.4, the poly(amino acid) is protonated, i.e. poly(H.Lys)n+, whereas at pD 12.1 only approximately 10% of the epsilon-amino groups are positively charged. The results in all three systems are consistent with the isodesmic model of indefinite non-cooperative stacking. The stacking tendency follows the series: ATP4- (K = 1.3 M-1; pD 8.4) < ATP4-/poly(H.Lys)n+ (K = 11.5 M-1; pD 8.4) > ATP4-/90% poly(Lys)/10% poly(H.Lys)n+ (K = 3.1 M-1; pD 12.1). It is evident that poly(H.Lys)n+ assists the association of ATP by a factor of approximately 10, and it is suggested that, via its positively charged epsilon-ammonium groups, poly(H.Lys)n+ acts as a matrix by aligning ATP4- ions via ionic interactions with the negatively charged phosphate residues. The intragranular concentrations of various constituents of several storage or secretory cell organelles, as reported in the literature, are tabulated. The chromaffin granules of the adrenal medulla and the dense granules of blood platelets contain particularly high concentrations of nucleotides ([ATP] is approximately 0.14 M in the chromaffin granules and 0.5 M in the dense granules of rabbit blood platelets) and amines, such as epinephrine or 5-hydroxytryptamine. These granules, and probably also the storage vesicles of certain neurons (which seem to have a similar composition), appear, if the total concentrations of the various solutes are considered, to be osmotically unstable, which means that the intragranular solutes must be associated. This aggregation is discussed, especially with regard to the nucleotides.
某些细胞器中高浓度ATP的出现促使我们通过研究在有和没有聚（α，L-赖氨酸）（其中[赖氨酸单元]为0.4 M）存在的情况下，于pD 8.4（25℃）的D2O中，0.0025 - 0.4 M范围内H2、H8和H1'的1H-NMR化学位移的浓度依赖性，来研究ATP的自缔合。在pD 12.1时重复了在聚（Lys）存在下的实验。在pD 8.4时，聚氨基酸被质子化，即聚（H.Lys）n +，而在pD 12.1时只有大约10%的ε-氨基带正电荷。所有三个体系的结果都与无限非协同堆积的等键模型一致。堆积倾向遵循以下顺序：ATP4-（K = 1.3 M-1；pD 8.4）＜ATP4-/聚（H.Lys）n +（K = 11.5 M-1；pD 8.4）＞ATP4-/90%聚（Lys）/10%聚（H.Lys）n +（K = 3.1 M-1；pD 12.1）。很明显，聚（H.Lys）n +使ATP的缔合增强了约10倍，并且有人提出，聚（H.Lys）n +通过其带正电荷的ε-铵基团，通过与带负电荷的磷酸残基的离子相互作用使ATP4-离子排列，从而起到基质的作用。文献中报道的几种储存或分泌细胞器的各种成分的颗粒内浓度被制成表格列出。肾上腺髓质的嗜铬颗粒和血小板的致密颗粒含有特别高浓度的核苷酸（在嗜铬颗粒中[ATP]约为0.14 M，在兔血小板的致密颗粒中为0.5 M）和胺类，如肾上腺素或5-羟色胺。如果考虑各种溶质的总浓度，这些颗粒以及某些神经元的储存小泡（其组成似乎相似）似乎在渗透上是不稳定的，这意味着颗粒内的溶质必须缔合。本文讨论了这种聚集现象，特别是关于核苷酸的聚集。
