COMPARE 39K TRANSVERSE RELAXATION IN VITRO SOLUTIONS & IN CYTOPLASM OF E COLI

在E.大肠杆菌， K+已被用于DNA分子相互作用的研究， 蛋白质、核糖体和离子。 在我们之前的实验中， 在致密的超导体中观察到了39 K的大横向弛豫速率， E. coli细胞。 由于K核的相互作用 与周围的电场梯度的DNA占主导地位， 在K-DNA溶液中加入少量盐， 这被认为是测量到的39 K弛豫的解释 in vivo. 然而，DNA溶液中39 K的弛豫速率，甚至 具有非常高的浓度（即，生理条件）， 比在体内慢得多 获得了类似的结果 浓缩的K-BSA和KCl溶液。 唯一的体外溶液， 产生同样大的横向弛豫 率在体内是核糖体的解决方案，高度负电荷 细胞中含有最多核酸的核糖体颗粒。 因此，核糖体颗粒被认为是 增强体内39 K的横向弛豫。 相似 横向弛豫特性也观察到， 23 Na-核糖体溶液。 这些结果需要进一步的实验 研究证实和探索核糖体的分子性质 粒子和K+，Na+-核糖体相互作用。 我们将使用DMX 400光谱仪与10毫米BB探头的39 K和23 Na（更多 敏感核）NMR研究。

The most abundant cation and osmolyte in the cytoplasm of E. coli, K+, has been used in studies of molecular interactions of DNA, proteins, ribosome and ions via 39K NMR. In our previous experiments, a large transverse relaxation rate of 39K has been observed in dense slurries of E. coli cells. Since the interaction of the K nucleus with the surrounding electric field gradient of the DNA dominants the 39K transverse relaxation in a K-DNA solution with little salt added, it was considered as the explanation for the 39K relaxation measured in vivo. However, the relaxation rate of 39K in DNA solutions, even with a very high concentration (i.e., physiological conditions), is much slower than that in vivo. Similar results were obtained for concentrated K-BSA and KCl solutions. The only in vitro solution that gives rise to the same large magnitude of the transverse relaxation rate as in vivo are ribosome solutions, the highly negative charged ribosome particles that have the most nucleic acids in the cell. Therefore, ribosome particles are considered as the key element that enhances the transverse relaxation of 39K in vivo. The similar characteristic of transverse relaxation was also observed in 23Na-ribosome solutions. These results require further experimental studies to confirm and to explore the molecular nature of the ribosome particle and K+, Na+-ribosome interactions. We will be using the DMX 400 spectrometer with the 10mm BB probe for both 39K and 23Na (a more sensitive nucleus) NMR studies.